5 sediment modelling tools

Progress Report No1

Mekong River Commission

Hydrological, Environmental and Socio-Economic Modelling

Tools for the Lower Mekong Basin Impact Assessment

Water Utilisation Programme

WUP-FIN Phase II

Working Paper No.1 – Model Development

April 2005

Juha Sark kula, Jorma Koponen, Marko Keskinen, Matti Kummu, Mira Käkönen, Hannu

Lauri, Jussi Nikula, Olli Varis, Noora Veijalainen, and Markku Virtanen

Finnish Environment Institute EIA Ltd.

Mechelininkatu 34a

00260 Helsinki

Tekniikantie 21 B

02150 Espoo

Finland

Tel: +358-9-403 000

Fax: +358-9-40300 390 www.environment.fi/syke juha.sarkkula@environment.fi

Finland jorma.koponen@eia.fi

Helsinki University of Technology

Water Resources Laboratory

Tietotie 1E

02150 Espoo, Finland

Tel: +358-9-7001 8680 Tel: +358-9-451 3821

Fax: +358-9-7001 8682 Fax: +358-9-451 3856 www.eia.fi

www.water.hut.fi/wr marko.keskinen@hut.fi www.eia.fi/wup-fin 1

Lower Mekong Basin modelling project, Mekong River Commission

2

The opinions and interpretations expressed within are those of the authors and do not necessarily reflect the views of the Mekong River Commission.

MRCS/WUP-FIN --- April 2005

Progress Report No1

TABLE OF CONTENTS

TABLE OF CONTENTS.................................................................................................. 3

TABLE OF FIGURES AND TABLES ............................................................................. 3

1 PROJECT OBJECTIVES ........................................................................................ 5

1.1

O BJECTIVES OF WUP-FIN PHASE II ...................................................................... 5

1.2

M AIN TASKS OF THE PROJECT ............................................................................... 6

2 MODEL APPLICATION AREAS ............................................................................. 8

3 HYDRODYNAMIC MODELING TOOLS ................................................................. 9

3.1

2D/3D L AKE , R ESERVOIR , C OASTAL AND F LOOD P LAIN M ODELS .......................... 9

3.2

1D/2D/3D C HANNEL M ODELS .............................................................................. 9

4 WATER QUALITY MODELLING TOOLS ............................................................. 10

5 SEDIMENT MODELLING TOOLS ........................................................................ 11

6 HYDROLOGICAL MODELLING TOOLS ............................................................. 12

7 DATA AND MODEL MANAGEMENT ................................................................... 13

8 DESCRIPTION OF THE MODEL DEVELOPMENT ACTIVITIES ........................ 14

8.1

TASK 1.2: HARMONIZED DATABASE AND MODEL ACCESS ..................... 14

8.2

TASK 1.3: A SET OF TOOLS FOR IMPACT ASSESSMENT .......................... 20

8.3

TASK 1.4: SEDIMENT MODEL FOR SELECTED LOCATIONS ..................... 28

APPENDIX A: PUBLICATIONS, REPORTS AND PRESENTATIONS ...................... 29

P

UBLICATIONS

............................................................................................................. 29

R

EPORTS

..................................................................................................................... 30

P

RESENTATIONS

.......................................................................................................... 30

REFERENCES .............................................................................................................. 32

TABLE OF FIGURES AND TABLES

Figure 11. WUP-FIN model areas. ............................................................................... 8

Figure 1. GIS data (BIL and ShapeFile) import into the model system. Colours show ground elevations (Digital Elevation Map, DEM). ............................ 17

Figure 2. Model results export into GIS-software (e.g. ArcView, ArcGis,

ArcInfo). Shown modelled sedimentation in the plain of reeds. ................ 17

Figure 3. Time-series input user interface. ............................................................... 18

Figure 4. Change in sedimentation between the baseline and high development scenarios in 1997. Observe decreased sedimentation

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except near the lake edge where flooding lasts longer in the high development scenario. ...............................................................................19

Figure 5. River cross-section representation in the 2D channel model. ...................20

Figure 6. River channel editor for the y-direction channels. Colours show ychannel widths and both x- and y-channels are marked with lines.

Observe nested Plain of Reeds high resolution application. .....................22

Figure 7. Schematic coupling of the hybrid channel/floodplain model components. ...............................................................................................23

Figure 8. Nested Vientiane river bank erosion model with 25 m resolution. .............27

Table 1. Planned and realized resources expenditure and percentage of task milestone reached. “Difference” is the difference between the spent and planned months. ........................ Ошибка! Закладка не определена.

Table 2. Gant-chart presenting the project activities according to the original project plan and the revised. ............ Ошибка! Закладка не определена.

Table 3. Decrease in sedimentation in the Tonle Sap Lake and floodplain in

1997 under the high development scenario compared to the baseline scenario. Division according to the elevation zones. ..................19

Table 4. Location and timings of village surveys in Mekong Delta and their linkage to model applications. .......... Ошибка! Закладка не определена.

4 MRCS/WUP-FIN --- April 2005

Progress Report No1

1 PROJECT OBJECTIVES

1.1 O

BJECTIVES OF

WUP-FIN

PHASE

II

The Finnish Environment Institute, in consortium with the Environmental Impact

Assessment Centre of Finland and the Helsinki University of Technology, contracted by the Mekong River Commission (MRC), is carrying out a project entitled Hydrological,

Environmental and Socio-Economic Modelling Tools for the Lower Mekong Basin

Impact Assessment. The project, also called the WUP-FIN Phase 2 Project, builds on past work, WUP-FIN Phase 1, completed by the same Finnish research team. WUP-

FIN project is a complementary project for the MRC Water Utilization Programme

(WUP).

The WUP-FIN Phase 2 Project will provide additional modelling tools, data, and training for the MRCS and the riparian National Mekong Committees (NMCs), line agencies and universities.

This research will be useful for several related MRC Programmes which are identified in the report. In addition, the research team strives to share data and conclusions with other related projects and plans.

The main objectives of the WUP-FIN Phase 2 Project are:

1. To complement the MRC Decision Support Framework (DSF) with WUP-FIN modelling tools to improve its hydrological, environmental and socio-economic impact assessment capabilities.

2. To provide technical support to the MRC programme activities, in particular the

Basin Development Plan (BDP) and Rule Formulation, by using the WUP-FIN modelling tools for: o Negotiating flow rules and equitable water utilization among the riparian countries (IBFM, WUP, EP) o Estimating environmental and socio-economic consequences of development scenarios (BDP), sustainable maintenance of fisheries

(FP) and navigational planning and impact assessment (NP)

3. To build capacity at the MRCS, the NMCs, related line agencies and other institutions to achieve sustainable use of the WUP-FIN modelling and impact assessment tools.

The project will focus on target areas in the following locations:



Lao PDR —The project will develop an advanced modelling tool to analyze river bank erosion processes and causes, focusing on the Vientiane area in Lao

PDR



Thailand —The Nam Songkhram watershed for simulation of hydrological processes and estimation of environmental and socio-economic impacts of development scenarios



Cambodia —Research will be undertaken to further understand processes in the Tonle Sap Lake and its impact on the region as well as the vulnerability of its ecosystem and biological productivity to developments in the upstream basin. Specific model will be constructed for the Chaktomuk area and

Cambodian floodplains



Vietnam —WUP-FIN models will be applied to the Mekong Delta to enhance understanding of the complex hydrological, ecosystem and socio-economic processes and understand how conflicting water needs can be met. Mekong

Delta model will be combined with the Cambodian floodplain and Tonle Sap models www.eia.fi/wup-fin 5


1.2 M AIN TASKS OF THE PROJECT

Task 1.1: Creation of a field measurements database for modelling

Additional data collection strives to complement the flow, salinity, turbidity and suspended sediments and dissolved oxygen databases in the target geographic areas.

The field measurement activities concentrate on three areas: Vientiane river bank erosion, Tonle Sap sedimentation and Vietnamese Delta flow, sediments and salinity.

Task 1.2: Database harmonization with the MRCS Geodatabase and DSF

The activities include analysis of MRCS Geodatabase, DSF and WUP-JICA data and tools, data interfacing and integration with the MRCS Geodatabase and guaranteeing easy access to the WUP-FIN models for the users as well as provision of WUP-FIN hydrological, water quality, ecological and socio-economic data import system to the

MRCS Geodatabase.

Task 1.3: Creation of a set of tools for impact assessment of the Lower Mekong

Activities include development of a hybrid 1D/2D/3D channel model integrating river and irrigation channels and control structures (gates, dikes, reservoirs etc.) and combination of the channel model with the 2D/3D model for floodplains, lakes, reservoirs and the coast. Further developments include a small scale channel hydrodynamics and storage model that is relevant especially for the Delta conditions and integration of the Lower Mekong sub-models (Tonle Sap, Cambodian floodplains,

Delta).

Task 1.4: Development of Lower Mekong sediment model

The activities comprise implementation of sediment transport in the hybrid 1D/2D/3D channel model, development of a bed load model as part of the hybrid model and description of different sediment fractions. The main target area for the sediment model development and application will be Vientiane, focusing on 3D river bank erosion modelling. The transport/ sedimentation/ erosion model will be applied also in

Tonle Sap and Chaktomuk area and in the Vietnam delta

Task 2.1: Technical advice and support to the MRC programmes and projects

The project will provide technical assistance for the Integrated Basin Flow

Management (IBFM) by assisting in defining acceptable Tonle Sap reverse flow and acceptable minimum and maximum flows (Article 6). It offers support in developing holistic approach for assessing ecological, economic and social consequences of particular flow regimes. The project provides technical assistance for the Basin

Development Plan (BDP) in sub-area analyses and forum process and in development scenario impact assessment. Socio-economic field surveys as well as diagnosis and policy recommendations studies will be performed in the Mekong Delta and other possible hotspot areas. An approach will be developed to integrate socio-economic data with hydrological and environmental information, applied in first place on Tonle

Sap area. Advanced Policy Models for the hotspot areas (Tonle Sap, Mekong Delta) as well as for the entire Lower Mekong Basin will be set up.

Task 3.1: Establishing MRCS’ and riparian countries’ capacity to use and maintain the modelling system

During this project MRCS, NMCs, national agencies, provincial departments and universities experts will be trained for sustainable use and maintenance of the modelling tools. Models will be established as everyday tools by cooperating closely with the MRCS programmes and working groups.


Progress Report No1

The main training target groups are:



The MRCS Modelling Team (Key Modellers and Associated Modellers) as the principal beneficiaries in the training programme. Training is composed of an introductory course, training for new developments and on-the-job training with the WUP-FIN team



Key National Trainees from the riparian countries and national model users selected from the NMCs, line agencies and universities. Training will be implemented by an introductory course and a National Training Workshops in each country. Core teams will be selected in each country for convening regularly and participating in model development as well as data acquisition and review.



University training will target an interdisciplinary group of university teachers and students. Training will be arranged in intensive periods in each country.

The trainee group will be collected from relevant universities. The training will be a lecture course with practical exercises in model use and application. It is likely that some of the university trainees will join the national core teams for more advanced model development and application. www.eia.fi/wup-fin 7


2 MODEL APPLICATION AREAS

8

Figure 1. WUP-FIN model areas.


3 HYDRODYNAMIC MODELING TOOLS

3.1 2D/3D L

AKE

, R

ESERVOIR

, C

OASTAL AND

F

LOOD

P

LAIN

M

ODELS

3.2 1D/2D/3D C HANNEL M ODELS

Progress Report No1 www.eia.fi/wup-fin 9


4 WATER QUALITY MODELLING TOOLS


5 SEDIMENT MODELLING TOOLS



6 HYDROLOGICAL MODELLING TOOLS


7 DATA AND MODEL MANAGEMENT



8 DESCRIPTION OF THE MODEL DEVELOPMENT ACTIVITIES

Model, data tools and modelling software development is the largest task for the WUP-

FIN-project within the MRCS. Below the modelling progress description is divided according to the outputs and activities defined in the project document.

8.1 TASK 1.2: HARMONIZED DATABASE AND MODEL ACCESS

The data needs for the WUP-FIN Phase II are broad and versatile. Data sources are spread out and data type variation is high. New types of GIS and time-series data pose new requirements for the system. For these reasons special attention has to be devoted to data access, management, integration, import and export. User community have to be supported with improved data functions for making the use of the modelling tools more efficient.

Analysis of Geodatabase, DSF, WUP-JICA and VIC data and tools

Geodatabase

In the past MRCS programmes and projects have relied on their own databases without a central database or general guidelines how to manage data. As part of the development of the MRC Information System, an MRC project is currently ongoing to develop MRC Information System Portal. This includes the creation of a centralized database (aka Geodatabase) and tools to search, view, and download data through a web portal. Technology consists of Oracle relational database and ESRI ArcSDE and

ArcIMS software. ArcIMS is used as the map server providing spatial data over the

Internet. System enables various monitoring and GIS data to be managed and distributed centrally. Development of the system is supported by the Canadian Centre for Remote Sensing and the National Resources Canada, and is managed by the

Hatfield Group, a Canadian based consultancy company.

Geodatabase will provide web-access to the MRCS internal and external data users.

The main potential from the WUP-FIN point of view is in the data distribution of the modelling results and possibly also other data products. A procedure for adding WUP-

FIN data to the Geodatabase should be created once the use of the WUP-FIN results has been consolidated. Users have recommended catalogue-like data access where processed model outputs are collected for easy reference. For instance scenario impact analyses could be examined and compared easily with this approach.

In exporting data into the Geodatabase metadata describing data format, accuracy, location, creator, owner etc. must be provided. The MRCS Metadata Standard has been publicized in March 18 2005. It is based on ISO 19115 Metadata Standard.

The data retrieval for modelling purposes is not expected to change appreciably compared to the older MRCS database (DBANK) because the GIS data formats will not change. Also the GIS data needed for modelling needs to be updated seldom. The access to the Geodatabase requires ArcGis version 9 or later.

DSF

DSF contains data from various sources such as MRCS, WUP-JICA and national institutes. It is usually more straightforward and transparent to use data directly from the primary sources than from the DSF. Exception is the schematizations and especially the river cross sections, which can be useful for the WUP-FIN LMB (Lower


www.eia.fi/wup-fin

Progress Report No1

Mekong Basin) model construction where primary data is not available. In general

WUP-FIN uses the new SRTM Digital Elevation Model (DEM), new WUP-FIN topographic survey maps for the Tonle Sap, Hydrographic Atlas and national

Vietnamese data in model construction in order to be based on the most up-to-date data.

Not all of the model cross sectional data contains explicit (x,y)-coordinates for each cross section point. Depending on the model it may be necessary to have also the directional data of the cross sections. For that reference point for each cross section has to be searched from a separate file, the direction of the cross section defined and each cross section point assigned (x,y)-coordinates.

The necessary data from the DSF are the scenario discharges at the WUP-FIN model boundaries. A program for importing the DSF time-series into the WUP-FIN system has been created for that purpose.

The main tools within DSF are models, model user interfaces and impact analysis tools.

Of these WUP-FIN utilizes mostly the modelling tools. DSF time-series files can be used as inputs to the WUP-FIN models. They supplement missing measurements and provide boundary values for the scenario runs.

DSF impact analysis tools consist of a) time-series, b) spatial and c) functional relationship analysis tools. WUP-FIN system contains integrated time-series and spatial data management, analysis and graphics tools, and there is usually no need to use external programs. There exists an export routine to transfer time-series data to the DSF if comparison or analysis is needed within the DSF. Spatial (raster) outputs from the WUP-FIN model can be either analyzed with the WUP-FIN integrated analysis tools or transferred to the DSF as GIS-files. The functional relationship analysis tools are user programmable tools residing outside the DSF and may be applied to the

WUP-FIN data if they will be someday developed.

One recurring request from the MRCS has been data and output harmonization for the different models (DSF, WUP-JICA and WUP-FIN). The DSF baseline flows were analyzed for the Tonle Sap and compared with the flows derived from discharge and water balance/lake volume measurements. There are differences between the ISIS and WUP-FIN synthesized flows. Detailed analysis is needed to understand them better and will be conducted time providing.

WUP-JICA and VIC

WUP-JICA data consists of both measurements and model input data. The field water level and discharge measurements in the Cambodian floodplains are quite valuable in model construction and verification. Also comparison between the WUP-JICA and

WUP-FIN simulation results will be informative and is requested by the MRCS for model harmonization. (The same applies to the DSF results.) The WUP-JICA and

WUP-FIN water balances (in- and out-flows) Tonle Sap have been compared and they are very similar.

Potentially useful WUP-JICA model data consists of river cross sections and infrastructure data. The same applies to the cross sections as was discussed under the DSF. Infrastructure data in general is the most lacking one and difficult to obtain.

WUP-JICA model data contains information about road heights and bridge dimensions which are important for the floodplain flow modelling. The data has been obtained for instance from Cambodian JICA-projects. The road embankment data is being prepared by the BDP. According to them it is “quite hard to get a schematic of the models to show which structures were explicitly modelled and which weren't - true for the DSF models too”. Also keeping the infrastructure data up-to-date is difficult.

WUP-JICA time-series files are binary format. Input files are in dsf0-format which can be accessed from ArcGis version 8.3 or higher when free DHI-software time-series package has been installed. The outputs are in MIKE11 res11-format and can be converted to ASCII csv-format (Comma Separated Values) with a free res11read.exe-

15

Lower Mekong Basin modelling project, Mekong River Commission program. WUP-JICA final report contains the model input and output time-series as well as the model cross-sections.

A number of hydrological models have been applied in the Mekong region. Basin-wide applications are Washington State University VIC and IWMI SLURP. More local applications include DSF SWAT for Lower Mekong, Washington State University

DHSVM for Chaem River Basin in Thailand and WUP-FIN VMOD and HBV and

JICA/DHI NAM in the Cambodian watersheds. Water resources management

(irrigation, urban water uptake, groundwater pumping, hydropower etc.) is included in these models to varying decrees. IQQM is a dedicated water resources management model that is used in the DSF-system. These models vary in respect to their

“physicality” which means the degree the physical processes are described explicitly versus them being parameterised or approximated conceptually. For instance physical models take into account the detailed topography and soil characteristics of the watershed and use hydrodynamic equations to route water through the terrain. The most explicitly physical model is VMOD followed by the DHSVM.

Washington State University VIC hydrological model covers the whole basin. It uses mostly public domain datasets as inputs. The research team has good connection to global climatic change research. The datasets used in VIC are to a large extent available at the MRCS and/ or from public domain and don’t bring any new information to the WUP-FIN. However the VIC model outputs would offer interesting comparison to the DSF. The VIC model covers whole basin and has been used for scenario runs and studies on the effect of Pacific on the basin hydrology. VIC could be run part of the

WUP-FIN system for creating boundary data for the local applications.

Primary data interfacing and integration with the Geodatabase

WUP-FIN has retrieved data from the MRCS GIS-databases in different formats. For the model system the data has to be in ESRI Shapefile vector or BIL binary raster formats. An example of ground elevation BIL-data (DEM) in the model system is

shown in Figure 2.

WUP-FIN raster (spatial) data export format to the Geodatabase is currently ESRI BIL

(Binary InterLeaver format, Figure 3). Also ShapeFiles are supported to a limited

extent although they are not intended for raster data.

The BIL format for import/export has been selected because it is not a protected format, in other words the files can be created from programs not dependent on ESRI modules, and it is quite compact. The downside of the format is that it is integer format necessitating scaling of output data and not suitable for data where large range of values are present. In ESRI software BIL-files can be exported only in ArcInfo which is much more expensive than for instance ArcView. Because of the limitations of the BILformat GeoTiff-format support is under development. GeoTiff is a floating point format and can the created from basic GIS-software. It is supported by a large number of different GIS software companies and can be considered a standard general GISformat.


Progress Report No1

Figure 2. GIS data (BIL and ShapeFile) import into the model system. Colours show ground elevations (Digital Elevation Map, DEM).

Figure 3. Model results export into GIS-software (e.g. ArcView, ArcGis, ArcInfo). Shown modelled sedimentation in the plain of reeds.

An important part of data export from WUP-FIN into the Geodatabase is metadata, the description of data quality, accuracy, location, data format, source, terms of usage etc.

There exist a number of metadata editors for creating the metadata header files.

Testing of M3Cat-program was suggested by the MRCS but program requires

Windows Information Server installation and its use as a separate program complicates data export. It has been decided that WUP-FIN will create the metadata xml-files as automatically as possible based on a few basic templates. The metadata creation should be an integral and automated part of the data export into the www.eia.fi/wup-fin 17


Geodatabase. The very recent publication of the official MRCS metadata format provides the necessary templates for WUP-FIN.

Guaranteeing easy access to the WUP-FIN models for the users

The accessibility of the WUP-FIN tools depends on three issues:

1. data import and export

2. data management and model control

3. model output analysis and creation of data products.

The first two issues have been highlighted by the initial training courses for the riparian countries and by the construction of the model applications. The last issue has been brought up by preparation of the scenario run outputs to the IBFM-process (Integrated

Basin Flow Management program).

Data import for raster data has been discussed above in connection with the

Geodatabase. Time-series data import/export is complicated by the multitude of nonstandard formats. A program has been created to facilitate time-series input. It has been integrated in the modelling and time-series management system. The input-

window is shown in Figure 4. User specifies the input and output files, time-series

location, variables that are input, header and comment lines to be skipped in the input file and date format. Files can be also given as a list which facilitates handling a large number of files. The outputs are in WUP-FIN standard time-series txd-format.

18

Figure 4. Time-series input user interface.

Time-series export is most done in tabular format as copy and paste. There is also an option to export time-series in a few formats into a file.

There have been no major changes in data management and model control functions compared to the WUP-FIN Phase I. However, a large number of minor changes and improvements have been made based on user feedback and observed bugs. Timeseries drawing and analysis, windows handling and use of rating curves and water level boundaries (coastal areas and rivers) has been improved. Time-series analysis supports now graphical/numerical calculation of water balances. For instance summation/subtraction/averaging of a large number of tributary flows can be easily accomplished. Multi-variable time-series support has been added as well as new time formats. Possibility to use high-frequency wind data has been added. River channel editing for specialized channel model has been added. Error handling of user inputs has been improved and the modelling system is now more robust than before. The


Progress Report No1 only observed stability problems are with the GIS analysis program. It seems that the problems are connected with memory allocation for raster files from different model runs where the flooded areas differ.

Model output analysis and data products development happens in relation with the

MRCS-programs. Currently the IBFM is the major user of WUP-FIN products and suggestions have been received from it concerning the outputs. The DSF-scenario impact analysis by IBFM, especially Hugh Cross, provides also some ideas in developing the data products. From the users point of view the results should be

reduced to a few simple indicators or numbers (Table 1). On the other hand there are

very important spatial and temporal characteristics which are lost by reduction (see

Figure 5). Because of this WUP-FIN proceeds in both lines by a) providing concise

numerical values (e.g. changes in average nutrient input between different scenarios) as well as b) indicative time-series and spatial distributions.

Table 1. Decrease in sedimentation in the Tonle Sap Lake and floodplain in 1997 under the high development scenario compared to the baseline scenario.

Division according to the elevation zones.

Figure 5. Change in sedimentation between the baseline and high development scenarios in 1997. Observe decreased sedimentation except near the lake edge where flooding lasts longer in the high development scenario.

The access to the results should be as easy as possible and a catalogue-like approach where a set of processed model run results are presented has been suggested. On the other hand basic model use is easy enough for the users to make their own runs and analyses. Model system is currently being used by other than project personnel for a number of studies such as climate change, socio-economics and water quality. www.eia.fi/wup-fin 19


Supplementing MRCS Geodatabase with the WUP-FIN data

This task deals with the delivery of WUP-FIN measurement database to the MRCS and exporting model results into the Geodatabase. The delivery has been pending partly because of the metadata format has not been defined and partly because necessary export tools, database and metadata preparation are quite time consuming.

The necessary templates have been published recently and can be used in the delivery. Currently the database is being supplemented with additional measurement data from the years 2003 and 2004. The database can be delivered when the data addition is finished and metadata has been prepared.

The Geodatabase will be supplemented with the WUP-FIN model results when the results have been consolidated and accepted by the MRCS. There has to be formal approval of the results before they can be shown to users outside the MRCS.

8.2 TASK 1.3: A SET OF TOOLS FOR IMPACT ASSESSMENT

This task is connected to preparing necessary model software support for the new applications. Many of the development tasks are connected with modelling of the channel network and combining it with the floodplain/lake model. Other tasks involve model data processing and utilization and preparing practical model applications.

Practicality means adaptable, modifiable and efficient enough solutions so that changes in the applications can be made in a flexible way and simulations can be accomplished within reasonable time.

Development of a hybrid 1D/2D/3D channel model

The first version of the channel model has been realized in the Nam Songkhram and

LMB (Lower Mekong Basin) models. The channel model is the basic 3D model with the addition of varying grid width and length. This way the longitudinal and transversal resolutions can be different and rivers can be modelled more accurately. The widths can be different for different layers so the river profile can be resolved even in the 2D

mode (longitudinal and vertical resolution), see Figure 6.

20

Figure 6. River cross-section representation in the 2D channel model.

Currently the channel and floodplain models are dependent on the same grid reference system. That means that for each channel model point there has to be exactly one corresponding floodplain point. The next development is to de-couple the models so that the grids are not directly dependent on each other.

The floodplain model will contain cells that are marked as “channel” and these are calculated in low water level with the dedicated channel model. If the water level is high enough, in other words flow is free between the surrounding floodplain and the river, these cells are switched to be calculated by the floodplain model. The floodplain


Progress Report No1 model software has to keep track on the channel/floodplain cells and change calculation schematization accordingly. In the channel model flooded river section water level, concentration etc. values have to be set from the floodplain model. The approach of clearly separating channel flow from the floodplain flow simplifies greatly model setup.

The model system has to maintain index tables where each channel model cell has reference to the overlapping floodplain cell and/or vice versa. This way the switching between flooded and channel cells can be managed easily.

If feasible, possibility to calculate the channels with a 1D model will be added to the system. Principally any 1D model can be used if it is possible to interface it with the floodplain model. WUP-FIN hydrological model VMOD 1D has been selected because of the accessibility, existing data routines and uniformity of the modelling system. Also use of the same 1D model throughout the model system helps future integration of the

3D and hydrological models. The VMOD 1D model has been developed to accommodate more options for hydrodynamics calculation (static, kinematic wave, kinematic wave + water level, and eventually full Saint-Venant).

The channel cross sections are available from different 1D models, such as ISIS,

Vietnamese National Model and WUP-JICA. For the smaller channels this data is quite useful. For the main channels original Hydrographic Atlas data may be more useful as it has been the basis of the model cross sections when available. The Hydrographic

Atlas data gives river depths relative to reference water levels defined every 1 km.

However, for modelling purposes river bed elevations are needed. WUP-FIN has transformed Hydrographic Atlas reference datum into digital format so that water depths can be transformed to elevations. What must be still developed is a program which assigns datum to each measurement point.

Development of a grid generation tool for the hybrid model

Structural and spatial data processing for model construction is often rather challenging. Spatial data is often extensive and its processing for modelling has to be automated. Spatial data includes:

 topographic data such as DEMs, lake and coastal depths and river cross sections

 vegetation and land use data

Structural data is discussed in connection with the model coupling.

Use of topographic data in modelling has two practical difficulties: 1) integration of the information from different sources with standard GIS-software may be difficult or impossible and 2) data has to be integrated/separated properly for the model purposes.

As an example of the first difficulty, a DEM doesn’t usually contain information of the river cross-sections and lake and coastal depths or the information is too inaccurate.

When the DEM is supplemented with measured crosssections and they don’t contain geographic x,y-coordinates for each section point, the data may be difficult to combine with the DEM. The second difficulty is illustrated with a case when the only information available is an integrated DEM combining river cross section data. It is difficult to retrieve specific channel elevations from the integrated DEM. To avoid these difficulties channel data should be specific for the channel model separate from the floodplain model DEM. However, channel data together with lake, reservoir and coastal bathymetry should be integrated into the floodplain model DEM when possible in order to make the floodplain model compatible with the channel model. This concerns especially the flooding case when channel grid cells are calculated with the floodplain model. www.eia.fi/wup-fin 21


Input of the channel information has three options for the current channel model:

1. giving channel widths for each model layer in tabular format

2. using graphical channel editor for the widths (Figure 7)

3. giving channel dimensions through a BIL-file.

The channel widths can be given separately for each layer in alternatives 1 and 2. This way the channel profile is accurate for different water levels. Mouse is used in the channel editor to define channel locations and keyboard for inputting the channel widths in a dialog.

When the BIL-file input is used the resolution of the BIL-file has to be same or better than the smallest channels that are described. The value for each BIL-grid point is the channel depth. Model can calculate from these values model river channel dimensions that correspond to the actual river volumes and widths.

As discussed above the creation of a GIS-raster data file for the river channels from cross-section data using standard GIS-software may be difficult. Because of this and because original cross-section data may be more appropriate at least in 1D-models alternative cross-section based input of the channel information is under development.

The exact realization of the channel data management software depends on the final realization of the channel model. The requirements for 3D and 1D models differ, because in 3D the directional information has to be maintained whereas in 1D it has no use. The grid generation tools and their requirements are also quite different in 3D and

1D. Probably the best strategy is to take the final 3D channel model as a basis for the cross-section management and grid generation tool. 1D model requirements will then be met by (minor) expansion of the tool to produce appropriate data for the 1D model.

The 2D model requires definition of the channel widths for each layer and this should be accomplished with the same grid generation software.

22

Figure 7. River channel editor for the y-direction channels. Colours show y-channel widths and both x- and y-channels are marked with lines. Observe nested

Plain of Reeds high resolution application.


Progress Report No1

The grid elevations for the floodplains, lakes and coastal areas can be given in four different ways:

 as BIL files directly from GIS-software

 as tables through model user interface

 manually with the model grid editor

 from a grid generation program which uses processed topographic information.

To streamline model grid generation GIS-based solution is under further development.

Currently the BIL-file elevations have to be in the model grid system. A more flexible way is to have the elevations in any resolution and from any area containing the model area. The model will have an integrated grid generation tool which will eliminate the need for intermediate steps for grid generation. As discussed above the BIL-format should be also replaced by the more flexible GeoTiff-format.

Land use and vegetation data is used both by the hydrodynamic and water quality models. In the hydrodynamic model it determines additional vegetation or structure friction as well as sheltering of the water surface. Both of these are dependent on the water and vegetation height so that for instance wind friction is affected if the tree tops are visible over the water surface. In the water quality model land use type determines sediment oxygen demand. Currently land use is input into the hydrodynamic model from a dedicated ASCII-file. The system is awkward and the exact correct placement of the land use types difficult to accomplish. Because of this the land use data for the model should be generated in a similar way as the topographic data.

Coupling of the channel model with 2D/3D model for floodplains, lakes, and reservoirs

Figure 8 illustrates the coupling of the different models in the hybrid channel/floodplain

model. The 1D river channel model can be connected longitudinally to the 2D/3D channel model. Both of these in turn can be connected laterally to the 3D (2D) floodplain and lake model. Hydrological model provides discharge data as boundary values for the channel and floodplain models.

Figure 8. Schematic coupling of the hybrid channel/floodplain model components.

As can be seen from Figure 8 there are two basic types of boundaries between the

channel and floodplain model: longitudinal channel – channel (or channel - lake) and transversal channel – floodplain ones. www.eia.fi/wup-fin 23


Channel – channel boundaries

Channel – channel boundaries are established for instance when part of the river system such as smaller tributaries are modelled with a 1D model and larger river channels with the basic 3D model or a 1D tributary enters flooded area. The lateral coupling is not straightforward because of the backwater effect and because flow direction can vary depending on time, depth and horizontal location. The boundary between models has to calculate material balances for both directions and provide compatible variable values (e.g. pressure) for both models. This is done in the basic model when different resolution models are nested. A corresponding material balance calculator and model equation transformer equations must be developed for the channel model boundaries also.

The coupling is prone to numerical instabilities and errors. This is because different model types and resolutions are used and because of values are interpolated and averaged on the boundary. Numerical filters are usually applied on the boundary to enable converging solution especially in the fully coupled case (signal travels in both directions over the border).

The coupling is greatly simplified when the coupled models are either largely compatible with each other or the flow is uni-directional on the boundary and there is no backwater effect. In the latter case the upstream model provides discharge, water level and concentration boundary values to the downstream one. There exists no feedback mechanism between the models and the solution is stable. Unfortunately backwater effect is quite prominent in the Vietnamese Delta and Cambodian floodplains.

The compatibility is utilized in the current channel model to facilitate coupling. The channel model is similar to the basic 3D model except it can use varying grid width in the lateral and longitudinal directions to describe the river channel dimensions. The models are coupled by default with each other except in areas where banks, dikes, road embankments etc. block the coupling. When the water level rises the channel model and surrounding flood plain model can become coupled in these points. The compatibility is partly lost in the next development phase when the grids of the channel and floodplain models don’t depend on each other any more.

For the coupling model has to maintain index tables defining the neighbouring model cells in different models.

Channel – floodplain boundaries

Channel – floodplain boundaries are the lateral boundaries in respect to the river channels. The coupling is of concern only when the channel is separated from the floodplain. The flooded channel points are part of the floodplain model.

In general the control and infrastructure points such as road embankments, dikes, bridges, gates and culverts are natural coupling or de-coupling points for the channel – floodplain interaction. In the model infrastructure data can be given in ASCII-files specifying the coordinates and type of each control. Alternatively dike information can be also input in a BIL GIS-file. The common data for all control types is:

 t1,t2 = control type, sub-type



(x1,y1) = start coordinates of the wall/dike



(x2,y2) = end coordinates of the wall/dike

Sub-type is the specific type under the general type or direction of a wall/dike. General control types are:

1. = wall (no overflow)

2. = dike, road embankment, weir etc. described with weir-flow formula


Progress Report No1

3. = water level gate (open/close depending water level)

4. = time gate (open/close depending on time), e.g. reservoir flow regulation

5. = dike/dam break.

Depending on the control type additional specifications are needed. For dikes height and width at the crest are given. Gates require discharge information. Water level gates require open/close water level height. Time gates and dike/dam breaks need times when the control opens or starts to break and when it is closed or is fully developed. Dike/dam breaks need in addition dimensions at the start and in the end of the break event.

It should be noted that the use of the control structures is not limited to the coupling boundaries. Currently these structures can be also used within the channel and floodplain models.

The control structure types or model equations are by no means fixed. The model data structures and control handling have been deliberately designed to be flexible so that new controls can be easily added or equations changed. A typical example would be addition of a reservoir gates which would function according to a specific operational rules.

The control structures handling is not yet supported by the user interface. Because of that the controls have to input with a text editor. This is a deliberate strategy because available infrastructure information availability and its format are largely unknown.

When during the project the information status is clarified appropriate user interface modules can be added.

For the coupling model has to maintain index tables connected to the control structures.

These tables indicate the channel and floodplain model cells on both sides of the control structure and determine the interacting cells.

Development of small scale channel hydrodynamics and storage

This tasks deals with modelling of small scale channels and ponds. Small scale means here that they can’t be modelled with available grid resolution or they are so numerous or complicated that it is not feasible to model them individually.

This task is scheduled to be realized later.

Establishment of a model database

The current model database contains raw and processed data from the first and second project phases. The detailed description of the Phase I data can be found project data reports. Description of the Phase II country specific data can be found in this report under the country activities. In addition MRCS Hymos and DBANK database data has been used extensively by the WUP-FIN.

Model database arrangement and maintenance is an ongoing task because new data is continuously added to it when the riparian countries have delivered it. By default the national data will be available only for the corresponding national teams. Availability of the model spatial data and input time series has to be clarified with the national institutes and NMCs.

Data integration into the model (GIS-based solution)

The data import, export, processing and integration are discussed in connection with other tasks. In practice it is not feasible to separate data and model development tasks totally because available data defines at least to some extent model structures and solutions and on the other hand model needs dictate data management and processing procedures. www.eia.fi/wup-fin 25


This task deals with the creation of appropriate common software platform for the use of GIS-data in the models. Functions that need to be developed include:



GeoTiff GIS support

 infra- and control structure input through GIS

 cross-section management and conversion

 editors for control structures, cross-sections and land use

 integration of data from various sources, especially topographic data.

This task is scheduled to be realized for the most part later.

Finding practical and efficient model realisation

The usability of the modelling tools is lost if they are computationally too heavy, that is the model computation times are extremely long. The parameters which govern the model execution times are:

 number of grid cells

 process time steps

 processes included in the model

 selected hydrodynamic equations

 grid cell dimensions

 maximum and minimum water depths

 friction calculation mode

 numerical solution method

 required accuracy

 coupling mode

 use of stored simulation values (e.g. flows and fetch)

 multiprocessing and parallelization

 compiler and operating system.

The task is scheduled at later part of the project, but already during the pilot phase attention has had to be devoted on the grid resolution and general set-up of the models. For instance the very high resolution (25 m) Vientiane river bank erosion model shown in figure 3.8 has proven to be too time consuming for longer runs.

However, it is suitable for more or less stationary case studies and for a few days simulations.


Progress Report No1

Figure 9. Nested Vientiane river bank erosion model with 25 m resolution.

Integration of sub-models (Tonle Sap, Cambodian floodplains, Delta)

The original plan for sub-model integration has been to develop each sub-model separately and integrated the models towards the end of the project. The problem with this approach is that boundary values are needed for each sub-model and it is impossible to separate isolated parts in Cambodian floodplain/Vietnamese Delta – system. For that reason the local applications can’t be developed in isolation from the

LMB-system.

In the Vietnamese Delta different approaches for calculating local high resolution applications together with other models are being tested. There are basically three approaches: 1) local models are calculated as nested coupled models within the LMBmodel, 2) boundary values are given off-line from the LMB-model and 3) boundary values are obtained from the DSF or Vietnamese National Model. The disadvantages of each approach is

1. nesting boundary affects the flow

2. a) solution is averaged in time because flow can’t be stored with same frequency as it is calculated, and b) high reso lution simulation doesn’t contribute to the coarser one

3. same as 2. + possible incompatibilities between the models.

The different approaches are compared throughout the project and the most suitable one is selected.

When the local applications have been developed they will be integrated into the regional LMBmodel. The integration doesn’t necessarily mean nesting of the models but also inclusion of the local model data, parameter values, approaches and solution methodology to the large scale model.

Sub-model for Thailand

Both the hydrological and hydrodynamic models have been set up for Nam Songkhram watershed in north-eastern Thailand. The model setup is described in more detail in the country specific activities chapter. www.eia.fi/wup-fin 27


The hydrological model used in the Nam Songkhram is an improved version of the

VMOD distributed hydrological model. Description of surface and subsurface water movement has been developed, soil types and differentiated processes for each type added, soil layers added, ground water description simplified, channel routing alternatives added (static, kinematic, kinematic + water level), water quality calculation support improved and erosion modelling implemented.

In the previous VMOD version groundwater flow was calculated with a 2D diffusion equation. Because in practice the soil properties are not known well in this approach the ground water flow is quite difficult to calibrate. A more straightforward storage-type approach has been substituted instead.

A manual for the Nam Songkhram VMOD model has been prepared. It details the model details and options.

The Nam Songkhram VMOD application is important for the maintenance and development of the modelling system. It is the only hydrological application in the

Phase II and will develop readiness and skills for advanced modelling. Hopefully the application will also contribute to the watershed management whether water use, fisheries and agricultural productivity, maintenance of habitats or water quality are under study.

The 3D model has been applied to the mainstream Mekong and the floodplains of Nam

Songkhram watershed. The purpose of the model is to study flooding in relation to tributaries and Mekong flows, effect of built structures on flooding and fish habitat and wetland productivity changes under different development scenarios.

8.3 TASK 1.4: SEDIMENT MODEL FOR SELECTED LOCATIONS

Sediment modelling and bank erosion approach has been presented in detail in the

Inception Report. The sediment model module has been programmed based on the equations presented in the report. The next step is to add the sediment model to the

3D model framework.

Vientiane model for calculating river bank erosion has been established. Field measurement program has been drafted and two field surveys conducted on the river.

Socio-economic study on bank erosion and morphological changes (e.g. island formation) has been conducted. This study gives insight on the historical development and mechanism of morphological changes as well as their socio-economic consequences. These activities are described in more detail under the country specific and socio-economic activities.


Progress Report No1

APPENDIX A: PUBLICATIONS, REPORTS AND PRESENTATIONS

The following publications, reports and presentations done by the team members are related to WUP-FIN project phase 2.

P UBLICATIONS

Keskinen, M., 2004. Participatory village surveys in water resources management - case from Tonle Sap Lake, 30th WEDC International Conference on People-Centred

Approaches to Water and Environmental Sanitation in Vientiane, Laos, October 2004.

Keskinen, M., 2005. Socio-Economic Impact Assessment of the Mekong Development

– Case Tonle Sap Lake, International Symposium of Role of water sciences in

Transboundary River Basin Management, March 2005. Ubon Ratchatani, Thailand.

Keskinen, M., Makkonen, K. and Varis, O., 2005. The Role of China and Cambodia in the Mekong Region. In: L. Jansky and M. Nakayama (Editors), Endangered

International Waters: Lessons from Domestic Security Issues. UNU Press.

Keskinen, M., Koponen, J., Kummu, M., Nikula, J. and Sarkkula, J., 2005. Integration of Socio-economic and Hydrological data in the Tonle Sap Lake, Cambodia. In: V.

Kachitvichyanukul, U. Purintrapiban and P. Utayopas (Editors), Proceedings of the

2005 International Conference on Simulation & Modeling, SimMod'05, Bangkok,

Thailand.

Koponen, J., Kummu, M. and Sarkkula, J., 2004. Modelling Tonle Sap Lake

Environmental Change, SIL XXIX International Congress of Limnology, Lahti, Finland.

Kummu, M., Koponen, J. and Sarkkula, J., 2004. Upstream impacts on Lower Mekong

Floodplains: Tonle Sap case study, Proceedings of the International Conference on

“Advances in Integrated Mekong River Management”, Vientiane, Lao PDR.

Kummu, M., Koponen, J. and Sarkkula, J., 2005. Modelling Sediment Transportation in

Tonle Sap Lake for Impact Assessment. In: V. Kachitvichyanukul, U. Purintrapiban and

P. Utayopas (Editors), Proceedings of the 2005 International Conference on Simulation

& Modeling, SimMod'05, Bangkok, Thailand.

Kummu, M., Koponen, J., and Sarkkula, J. 2005. Assessing Impacts of the Mekong development in the Tonle Sap Lake, International Symposium of Role of water sciences in Transboundary River Basin Management, March 2005. Ubon Ratchatani,

Thailand.

Sarkkula, J., Kiirikki, M., Koponen, J. and Kummu, M., 2003. Ecosystem processes of the Tonle Sap Lake, Ecotone II - 1 workshop, Phnom Penh/Siem Reap, Cambodia.

Sarkkula, J., Baran, E., Chheng, P., Keskinen, M., Koponen, J. and Kummu, M., 2004.

Tonle Sap Pulsing System and Fisheries Productivity, SIL XXIX International Congress of Limnology, Lahti, Finland.

Sarkkula, J., Koponen, J., Kummu, M., Keskinen, M. and Varis, O., 2005. Integrated modelling for impact assessment in Mekong Delta and Cambodian floodplains,

International Conference on Deltas: Geological modelling and Management, Ho Chi

Minh City, Vietnam. January, 2005.

Sarkkula, J., Koponen, J. and Kummu, M., 2005. Assessing Impacts of the Mekong development in the Tonle Sap Lake, International symposium on Role of Water www.eia.fi/wup-fin 29


Sciences in Transboundary River Basin Management, Ubon Ratchathani, Thailand.

March, 2005. van Zalinge, N., Loeung, D., Pengbun, N., Sarkkula, J. and Koponen, J., 2003.

Mekong flood levels and Tonle Sap fish catches, Second International Symposium on the Management of Large Rivers for Fisheries, Phnom Penh, Cambodia, 11-14

February 2003.

Varis, O. & Keskinen, M. 2005. A Bayesian net-work model for intersectorial policy analysis in the Tonle Sap area, Cambodia. In: Kachitvichyanukul, V., Purintrapiban, U.

& Utayopas, P. (Eds.): Simulation and Modelling: Integrating Sciences and Technology for Effective Resource Management: 280-288. International Conference on Simulation and Modelling, January 17-19, Asian Institute of Technology, Bangkok.

WUP-FIN, 2003. Modelling Tonle Sap for Environmental Impact Assessment and

Management Support. MRCS / WUP-FIN Project, Final Report, Mekong River

Commission, Phnom Penh.

R EPORTS

Keskinen, M. and Varis, O., 2004. WUP-FIN Policy Model – Analysing the strategies of the Tonle Sap Sub-Area Analysis Process. Draft Report, Mekong River Commission,

Water Utilisation Programme Component FIN, Phase 2. Vientiane, Lao PDR.

Keskinen, M., Sambo, Y., Pok, N. and Oeurn, S., 2004. In the bend of the Bassac

River – Participatory village survey in Chheu Khmau Commune, Cambodia. Draft

Report, Mekong River Commission, Water Utilisation Programme Component FIN,

Phase 2. Vientiane, Lao PDR.

Keskinen, M., Sambo, Y., Pok, N, Samon, C. and Kamara Y., 2004. Living in the

Mekong Floodplain – Participatory village survey in Preah Sdach Commune,

Cambodia. Draft Report, Mekong River Commission, Water Utilisation Programme

Component FIN, Phase 2. Vientiane, Lao PDR.

Nikula, J., 2005. Integration of hydrological and socio-economic information in the

Tonle Sap Lake. Draft Report, Mekong River Commission, Water Utilisation

Programme Component FIN, Phase 2. Vientiane, Lao PDR.

WUP-FIN. 2005. Hydrological, Environmental and Socio-Economic Modelling Tools for the Lower Mekong Basin Impact Assessment: Inception report. Mekong River

Commission, Water Utilisation Programme Component FIN, phase 2. Vientiane, Lao

PDR.

P RESENTATIONS

At International Symposium on Role of Water Sciences in Transboundary River Basin

Management in Ubon Ratchathani, Thailand, March 2005. Socio-Economic Impact

Assessment of the Mekong Development – Case Tonle Sap Lake.

At International Symposium of Role of water sciences in Transboundary River Basin

Management, March 2005. Ubon Ratchatani, Thailand. Assessing Impacts of the

Mekong development in the Tonle Sap Lake.

At International Conference on Simulation & Modeling, SimMod'05, Bangkok, Thailand.

January 2005. A Bayesian net-work model for intersectorial policy analysis in the Tonle

Sap area, Cambodia.


Progress Report No1


January 2005. Integration of Socio-economic and Hydrological data in the Tonle Sap

Lake, Cambodia.


January 2005. Modelling Sediment Transportation in Tonle Sap Lake for Impact

Assessment.

At International Conference on Deltas, Geological modelling and Management. Ho Chi

Minh City, Vietnam. January 2005. Integrated modelling for impact assessment in

Mekong Delta and Cambodian floodplains. Keynote speech.

At Geography seminar series 2004-2005 in Department of Geography, National

University of Singapore. December 2004.Sediment and ecosystem of the Tonle Sap

Lake.

At 30th WEDC International Conference on People-Centred Approaches to Water and

Environmental Sanitation in Vientiane, Laos, October 2004. Participatory village surveys in water resources management - case from Tonle Sap Lake

At IAG 2nd Yangtze Fluvial Conference, Shanghai, China. June, 2004. Sedimentation and Mekong Upstream Development: Impacts on the Lower Mekong Basin.

At Computational Earth Science seminar, Finnish IT Centre for Science (CSC), May

2004. Modelling sediment transportation in alluvial system. www.eia.fi/wup-fin 31


REFERENCES

WUP-FIN, 2003. Modelling Tonle Sap for Environmental Impact Assessment and

Management Support . MRCS / WUP-FIN Project, Final Report, Mekong River

Commission, Phnom Penh.


5 sediment modelling tools

Hydrological, Environmental and Socio-Economic Modelling

Tools for the Lower Mekong Basin Impact Assessment

TABLE OF CONTENTS

TABLE OF FIGURES AND TABLES

1 PROJECT OBJECTIVES

2 MODEL APPLICATION AREAS

3 HYDRODYNAMIC MODELING TOOLS

4 WATER QUALITY MODELLING TOOLS