Establishment of a hydrological monitoring network in a tropical African catchment using integrated participatory approach: Case of Ngerengere River Catchment in Tanzania
M.C. Gomani 1&2* , O. Dietrich 1 , G. Lischeid 1 , H. Mahoo 2 , F. Mahay 3 , B. Mbilinyi 2 and J. Sarmett 3
1 Leibniz Centre for Agricultural Landscape Research, Institute of Landscape Hydrology, Eberswalder Str 84, D-15374
Müncheberg, Germany.
2 Sokoine University of Agriculture, Agricultural Engineering Department, P.O. Box 3151, Morogoro, Tanzania.
3 Wami Ruvu Basin Water Office, Mazimbu Road, P.O. Box 826, Morogoro, Tanzania.
*Corresponding Author Email: gomani@zalf.de
Abstract
Sound decision making for water resources management has to be based on good knowledge on the dominant hydrological processes of a catchment and this information can only be obtained through establishing suitable hydrological monitoring networks. Research catchments are typically established without involving the key stakeholders, which results in instruments being installed at wrong places as well as risk of theft and vandalism. This paper presents an integrated participatory approach for establishing a hydrological monitoring network. The approach consists of six steps beginning with (i) inception of idea; (ii) stakeholder identification; (iii) defining the scope of the network; (iv) installation; (v) monitoring; and (vi) feedback mechanism which are integrated within participatory framework. The approach is illustrated using an example of Ngerengere catchment in Tanzania. In applying the approach, the concept of establishing the Ngerengere catchment monitoring network was initiated in 2008 within the Resilient Agro-landscapes to
Climate Change in Tanzania (ReACCT) research program. The main stakeholders included: local communities; Sokoine
University of Agriculture; Wami Ruvu Basin Water Office and ReACCT Research team. The scope of the network was based on expert experience in similar projects and lessons learnt from literature review of similar projects from elsewhere integrated with local expert knowledge. The installations involved reconnaissance surveys, detailed surveys, and expert consultations to identify best sites. First, Digital Evelation Model, land-use and soil maps were used to identify potential monitoring sites. Local and expert knowledge was collected on flow regimes, indicators of shallow groundwater plant species, precipitation pattern, vegetation and soil types. This information was integrated and used to site locations for installation of an automatic weather station, automatic rain gauges, river flow gauging stations, flow measurement sites and shallow ground water wells. The network is now used to monitor hydro-meteorological parameters in collaboration with key stakeholders in the catchment and preliminary results indicate the network is working well. The benefits of this approach compared to conventional narrow scientific/technical approach have been shown by gaining rapid insight into the hydrology of the catchment, identifying best sites for installing the instruments; voluntary participation of
1

stakeholders in installation, monitoring and safeguarding the installations. This approach has proved simple yet effective and yielding good results. Based on this experience gained in applying the approach in establishing the Ngerengere catchment monitoring network, we conclude that integrated participatory approach helps to assimilate local and expert knowledge in catchment monitoring which consequently results in: (i) identifying best sites for the hydrologic monitoring; (ii) instilling the sense of ownership; (iii) providing security of the installed network and (iv) minimizing costs for installation and monitoring.
Key words: catchment monitoring, experiences learned, hydrological processes, participatory approach, Tanzania.
1.0
Introduction
Sound decision making for water resources management has to be based on good knowledge on the dominant hydrological processes of a catchment. This information can only be obtained through establishing networks that are capable of monitoring such hydrological processes at different temporal and spatial scales. The establishment of a catchment monitoring network involves a process, from inception of the idea to the actual construction of the various structures and installation of the necessary equipment and instruments while engaging relevant stakeholders. This process is usually driven by the intention of attaining definite research objectives (Wigmosta and Burges, 1997; Gilvear and
Bradley, 2000; Hodgson et al., 2002; Ireson et al., 2006). However, research catchments are typically established in areas where people do not live or people are usually excluded from such catchments (Kongo et al., 2007). This results in the risk of theft and vandalism. Unfortunately, establishment of hydrological monitoring systems in many catchments have tended to ignore key stakeholders.
With increased need for adequate understanding of hydrological processes at catchment scale, sustainable hydrological monitoring systems are needed to monitor these processes. However, establishing hydrological monitoring systems is not an easy task. Several studies have reported several drawbacks in establishing hydrological monitoring systems
(Mierovicz et al., 1998). Mul (2009) reported the following problems in establishing hydrological monitoring system in
Makanya catchment in Tanzania: (i) some equipment were installed at a wrong place due to limited knowledge of the areas’ characteristics; (ii) some were stolen and (iii) some were damaged by high floods. To address these challenges an approach is needed that integrates expert knowledge and local knowledge within a participatory framework.
2

There are few case studies in the existing literature on the establishment of catchment monitoring networks through a participatory approach involving the local community and other key stakeholders. Lorata et al . (2006) indicated the desire by local communities and other stakeholders to be involved in water quality monitoring and surveillance in the
Mzingwane catchment in Zimbabwe, even though they were not aware of the existence of such a monitoring program in their locality. Kongo et al.
(2007) suggests that the participatory approach in catchment monitoring has long term benefits including the opportunity for the relevant stakeholders, notably the local community, to gain insight into the hydrological regime of their locality. This in turn provides a good basis for decision making for farming activities and understanding the impact of various factors on water resources in the catchment. Thus, a participatory approach requires a constant effort to initiate a learning process, through which the key stakeholders are able to appreciate and recognize the importance of catchment monitoring as well as participate in the monitoring exercise.
Despite these benefits, to date this topic has been disproportionately under researched particularly in African tropical catchments. In this paper, we report on the establishment and installation of various instruments and structures for a catchment monitoring network that took place in the Ngerengere River in the Upper Ruvu River Basin, Tanzania. This provides a good case study for considering many issues and challenges (social, scientific and engineering) that need to be addressed in the process of establishing a monitoring network in a tropical small catchment in a developing region. The approach ensures developing synergies and building capacity for long-term hydrological monitoring and forecasting systems.
The present paper is one milestone of an ongoing project titled – ‘Resilient Agro-Landscapes to Climate Change in
Tanzania (ReACCT)’ – the hydrology sub-project. It crystallizes our current experience in establishing a catchment monitoring network aimed at fulfilling a threefold mission in line with the project’s overall objectives namely: assessing impacts of climate change and land-use options on the hydrological cycle in a small tropical African catchment. The specific objectives of establishing the Ngerengere catchment hydrologic monitoring network using a participatory approach include the following:
– Monitor the hydro-climatological processes of the catchment in order to gain an in-depth understanding of the hydrological regime and investigate the hydrological implications of climate change and possible land-use options;
– Build capacity to monitor water resources in the catchment in collaboration with key stakeholders through training on the basic methodologies of catchment monitoring; and
3

– Providing an opportunity for future and further research. This is due to the fact that the network comprises several permanent structures.
According to Hisschemöller et al.
(2001) an integrated participatory approach can be defined as an interdisciplinary process of combining, interpreting and communicating knowledge from diverse scientific disciplines in such a way that a problem can be evaluated from a synoptic perspective with two characteristics. First, the approach should have added value compared to single disciplinary approach and second the approach should provide useful information for decision making.
2.0
Study area
The Ngerengere catchment is located in the Upper Ruvu River Basin. It is within the longitudes 37°32’E, 38°09’E,
37°38E & 38°38’E and latitudes 6°51’S, 6°69’S, 7°09S, 7°05’S (Figure 1). The size of the catchment is approximately
2780 km 2 . The catchment is located in tropical climate region. There are two main rainy seasons, heavy and long rains prevail from March to May while short rains occur from October to December. The annual rainfall over most parts of the basin varies between 800 mm to 1000 mm except for the Uluguru Mountains where the mean rainfall increases to over
1500 mm (Mwandosya et al., 1998). The analysis of existing rainfall data indicates high spatial and temporal variability in the catchment. Daily temperature ranges between 22 °C and 33 °C. Normally, evaporation is higher than rainfall in the catchment. Monthly Penman potential evapotranspiration is 2000 mm per year in the basin and between 1600 to 1800 mm per year in the Uluguru Mountains (Mwandosya et al., 1998). The topography of the area ranges from relatively flat land to mountainous areas up to 2500 m above sea level in the Uluguru Mountains. (insert figure 1)
The geology of the catchment is mainly dominated by the Precambian Usagarian system that has underwent different plutonic history and Neogene although patches of Jurrassic, Karoo, Neogene and Quaternary exist in some parts of the catchment. Two main types of aquifers exist in the catchment namely the high yielding Quaternary aquifer (>100 litres per minute) which dominates the area and the low yielding Neogene aquifer (24.5 litres per minute) consisting of mainly sandy clays and clay sand (Kalugendo 2008). This background information is used as a basis for developing the
Ngerengere catchment monitoring system.
4

Climate and land-use change are already posing significant impacts in the Upper Ruvu River Basin. Mwandosya et al .
1998 predicted that the discharge of Ruvu River will diminish by 10% by 2010. In line with Mwandosya’s findings, studies by Yanda and Munishi (2007) revealed rapid land-use change and diminishing flows of the Upper Ruvu River.
Similar scenario is also speculated for ground water resources (Kalugendo, 2008). These observations are in line with many Global Circulation Models (GCM) predictions for the region which project changes in temperature and rainfall pattern as well as significant reductions in the length of the growing period (Thornton et al., 2006). Climate change will therefore aggravate water resource problems in the catchment possibly through increased frequency and intensity of droughts in some areas and flooding in other areas. Monitoring of hydrological processes in the catchment is therefore a key step towards understanding these processes.
3.0
Methodology
3.1 The integrated participatory framework
Many approaches have been used in establishing hydrological monitoring networks. Chow et al.
(1988) gives an example of a sequence of logical steps which are commonly followed for hydrological measurements and monitoring where inputs from key stakeholders is not integrated. In this study, the proposed approach has six steps beginning with (i) inception of idea; (ii) stakeholder identification; (iii) defining the scope of the network; (iv) installation; (v) monitoring; and (vi) feedback mechanism integrated within participatory framework (Figure 2). This approach was used during the establishment of the Ngerengere catchment monitoring network. (insert figure 2)
3.2 The integrated participatory process
3.2.1 Step 1: Inception of idea
The first step is the development of the concept of the monitoring system. This depends on objectives of the monitoring network. Specific questions need to be addressed include: (i) What should be the spatial boundaries of the monitoring system? (ii) What are the key hydrological processes that needs to be monitored and how? (iii) Is there any existing monitoring system? (iv) What is the historical profile of the system? (v) How did it get to be what it is now—what changes occurred through its history in terms of climate, land-use etc? —Careful analysis of historical profiles reveals a great deal about current system dynamics and how the system might respond to future external shocks; and (vi) How do the current institutional arrangements, property rights, distribution of power, formal and informal decision making and
5

access to information? The product of this step is a conceptual framework embodying what is known about the study catchment. It provides an essential basis for step 2 and it defines the “of what” part of the monitoring system.
3.2.2 Step 2: Stakeholder identification
The second step is identifying key stakeholders. The actual procedure will vary from region to region, depending on the levels of knowledge, experience and expertise available, but it will address specific questions such as: (i) Who are the key stakeholders? (ii) What are there interests and expectations? (iii) How should they be involved? (iv) When should they be involved? and (v) What can they contribute? etc
3.2.3 Step 3: Defining the scope of the monitoring network
Step 3 examines the scope of the monitoring network with the desirable objectives expected to be fulfilled. The aim is to develop a viable monitoring system that can be implemented with available resources. Objectives about preferred network will differ among stakeholder groups and the actual network will be the outcome of stakeholder consensus of what can be attained with available resources. The first priority in this step, therefore, is to establish a range of possible networks. The scope is developed by considering, in parallel, key hydrological processes that needs to be monitored, resources available and scope of existing network, if any. The process is iterative and begins with discussions among stakeholders, policy makers, other local experts, and scientists to build a common understanding of the system.
3.2.4 Step 4: Installation
First available information is gathered. Expert and local knowledge is integrated first to identify suitable sites. Site surveys are conducted to collect more information. Detailed designs of the network are then prepared and instruments are installed on selected sites that can monitor the processes of concern in collaboration with key stakeholders.
3.2.5 Step 5: Monitoring
The fifth step involves monitoring the hydrological processes of the catchment in collaboration with the key stakeholders. Where resources are limited integration of local communities in monitoring helps to reduce the costs and enhance stakeholder understanding on the processes monitored.
6

3.2.6 Step 6: Feedback mechanism
The final step involves stakeholder evaluation of the whole process and the implications of the data for decision making.
A feedback mechanism (Stage 5 - Figure 2) helps to incorporate emerging concerns and improves the efficiency of the monitoring system.
The goal of integrated participatory process is therefore to provide an interdisciplinary framework of combining, interpreting and communicating knowledge from diverse scientific disciplines in such a way that the approach should have added value compared to single disciplinary approach. In addition, the approach should provide useful information to assist in decision making.
4.0
Application of the integrated participatory process - an example in the Ngerengere catchment
The integrated participatory framework (Figure 2) was successfully applied in establishing the Ngerengere catchment monitoring network. The process involved inception of the idea, identifying key stakeholders, defining the scope of the network, installation and getting feedback from relevant stakeholders. Results and experience of this application are given below.
4.1 Step 1: Inception of the idea
The process of establishing the Ngerengere catchment monitoring network was initiated in 2008 within the ReACCT research program. The objectives of the network are given in section 1. The process integrated a participatory approach where key stakeholders were consulted on the concept and experience was integrated. Preliminary information about the catchment was collected on existing network and combined with experience from some stakeholders.
4.2 Step 2: Stakeholder identification
Stakeholders were identified during a field appraisal in November 2008. The main stakeholders at various degrees of participation, included the following (i) smallholder farmers actively participated in various experimental and monitoring activities, (ii) members of the local community in the Ngerengere catchment were involved in observation and construction, (iii) the traditional and local leadership were involved in assembling and motivating the community, (iv) the
Sokoine University of Agriculture (vi) the Wami Ruvu Basin Water Office and (vii) ReACCT Research team. The researchers managed to effectively use the existing organization structures previously put in place in the area for establishing contact with stakeholders who were willing to participate in the establishing the monitoring network. It is
7

through such forums that a good working relationship between the ReACCT research team and key stakeholders in the area was established.
4.3 Step 3: Defining the scope of the network
ReaCCT staff expert knowledge based on their experience in similar projects and lessons learnt from literature review of similar projects from elsewhere was integrated with local expert knowledge to define the scope of the network in collaboration with stakeholders. The agreed scope included an automatic weather station, three automatic rain gauges, three automatic gauging stations, nine shallow groundwater wells and six diviner wells. In addition mobile systems for monitoring Leaf Area Index (LAI) using Accur Ceptometer LP80 and Albedo using pyranomers equipped with UGT data logger as well as laboratory equipment (HYPROP System) for measuring soil hydraulic properties were added.
4.4 Step 4: Installation
Installation involved a participatory process and a scientific approach which entailed the application of scientific and engineering principles in designing, construction and installation of various structures and instruments. It should be noted that the two approaches were not treated separately but rather formed an integrated continuous learning process where the relevant stakeholders and researchers made an effort to interact and to learn from each other.
4.4.1 Selection of installation sites
The establishment of the Ngerengere catchment monitoring network involved the initial stage of reconnaissance surveys to gain a general understanding of the catchment before detailed and specific site surveys were performed as per requirements of each structure or instrument. The siting of the hydrological monitoring network in the catchment involved the application of expert knowledge, local knowledge, scientific and engineering techniques as well as consideration of existing network in the catchment. First DEM, land-use and soil maps were used to identify potential monitoring sites. Local and expert knowledge was collected on flow regimes, indicators of shallow ground water plant species, precipitation pattern, vegetation and soil types. This knowledge was integrated and used to site a network of ten hydrologic monitoring plots for vegetation and soil surveys and locations for installation of automatic weather station, automatic rain gauges, river flow gauging stations, flow measurement sites and shallow groundwater wells. Knowledge on historical peak flows and flood prone areas was vital during the design and construction of the stream flow measuring structures and shallow ground water wells.
8

4.4.1.1 Weather station
Information of existing weather stations and other stations near the catchment was collected. There was one complete weather station in the catchment operated by Tanzania Meteorological Agency (TMA). The second nearby station outside the catchment was about 50 km west, at Dakawa close to the Wami River. Stakeholders and project partners were consulted regarding the suitable site. Based on these consultations, Lukwambe in the middle part of the catchment was chosen because the area had no meteorological infrastructure (Figure 3). An automatic weather station (with rain gauge, solar radiation sensor, temperature sensor, relative humidity sensor and wind speed sensor) was installed in collaboration with key stakeholders. Local artisans were involved in electing the fence and villagers living close by provide security for the station. It is envisaged that data from the station can guide farming activities in the nearby farm.
4.4.1.2 Rain gauges
In the selection of suitable sites for rain gauges, information was collected on existing rain gauges and their types. There were eight rain gauges in the catchment. Existing rain gauges were not uniformly distributed within the catchment. Most of these were located in the mountainous part of the catchment. There was no rain gauge in the middle part of the catchment and only one in the lower part of the catchment. Based on this information, three additional automatic rain gauges were installed to complement the existing system (Figure 3). One rain gauge was installed in the upper part in
Mlali close to an existing manual rain gauge to compare measurements from the manual system with an automatic rain gauge. One rain gauge was installed in the middle part of the catchment close to Kingolwira gauging station. The third rain gauge was installed in the lower part of the catchment at Lukose Primary School. In this station, teachers, communities and primary school pupils participated in the siting and installation. Suitable sites were therefore selected to ensure good distribution of the rain gauges in the catchment. (insert figure 3)
4.4.1.3 Gauging stations and discharge measurements
In siting the gauging stations, information regarding existing stations was obtained and field visits to all stations was conducted in collaboration with key stakeholders. The catchment has four gauging stations. Two gauging stations are in the mountainous part in Ngerengere and Morogoro River tributaries. There are numerous tributaries in the mountainous part that are ungauged. The third (Mgude) and the fourth (Utari) gauging stations are located in the lower part of the catchment. Unfortunately, the last gauging station in the lower part was vandalized before the ReACCT project. Based on this information and the structure of the catchment, it was important to install two additional gauging stations in the
9

middle part of the catchment (one at Kingolwira and one at Lukwambe) to monitor discharge in this part and to rehabilitate the outlet gauging station to complement the existing system. The Kingolwira station measures discharge from all mountainous rivers while Lukwambe is able to measure discharge from the all major tributaries in the middle part of the catchment (Figure 3). Discharge measurements were then done for different water levels using Acoustic
Digital Current (ADC) flow meter at the new gauging stations to develop rating curves and existing stations to improve the old rating curves.
4.4.1.4 Shallow groundwater wells
First local expert knowledge was solicited on existence of shallow groundwater in the catchment. This was followed by field surveys to potential sites in collaboration with local experts and communities in the catchment. The catchment had no shallow groundwater observation wells. Based on this information, four potential sites were identified by integrating knowledge from experts, local knowledge experts on shallow ground water indicator tree species and existing domestic boreholes. Permission was sought from the local leaders and individual farmers to allow the auguring of the holes in some of the farms. The shallow groundwater wells were then designed by the Wami Ruvu Basin Water Office experts.
Three transects, two on one side of the river and one on the other side of the river, were identified and nine wells were installed. The transects were more or less perpendicular to the general slope of the catchment and the river. The location of the shallow groundwater wells in the catchment is as shown in Figure 3. Local artisans and communities were then involved in installation of the wells under the supervision of experts (Figure 4). Pressure transducers were then installed in two of the nine the shallow groundwater wells, after a calibration exercise, and linked to OTT data loggers which recorded the fluctuation of the water table and secured in metallic safe boxes embedded in concrete to safeguard the data loggers. Table 1 summarises information of shallow groundwater wells. (insert figure 4 and table 1)
4.4.1.5 Hydro-plots
Hydro-plots are experimental plots where a number of measurements are taken. In this project, the hydro-plots were designed to monitor vegetation parameters and quantify soil hydraulic properties. First Digital Evevation Model (DEM), land-use and soil maps were used to identify potential monitoring sites. Local and expert knowledge was collected on vegetation types, soil types and integrated in choosing the locations of the plots. Ten hydro-plots, representing different land-use, soil types and topography were identified (Figure 3). Communities assisted in marking the plots and digging soil profile pits. Six diviner tubes were installed in six of the ten plots to monitor volumetric water content in the hydroplots.
10

4.5 Step 5: Monitoring results from the network
The Ngerengere catchment hydrological monitoring network is now being used to monitor hydro-meteorological parameters. This is done in collaboration with all key stakeholders in the catchment. The network is working well. The instrumentation which forms the Ngerengere hydrological monitoring network ranges in sophistication from simple manually recording gauges, to state of the art instruments such as an automatic weather station and shallow ground wells equipped with automatic data loggers. Currently the system involves: discharge measurements using floater with encoder and data logger; discharge monitoring using Acoustic Digital Current (ADC) flow meter; climatic parameters monitoring using rain gauges and automatic weather station; diviner wells, shallow groundwater monitoring in 9 wells; deep groundwater monitoring using existing boreholes, mobile systems for measuring vegetation parameters (LAI and Albedo measurements), laboratory HYPROP system for quantifying hydraulic properties in hydro-plots;. The following sections give an overview of some selected example results from the network.
4.5.1 Climatic parameters monitoring
Rainfall is recorded using automatic rain gauges with data loggers as well as the automatic weather station. The automatic weather station is looked after by the owner of the farm. Example of some climatic parameters measured at
Lukwambe gauging station is given in Figure 5. The results show high diurnal variation of temperature and air humidity.
(insert figure 5)
4.5.2 Discharge monitoring using floater with encoder and data logger
The choice of using any of the stream flow monitoring structures depends on a number of factors, one being the geometry of the stream channel at the gauging site. For example, in wide channel sections where the construction of a flume or a weir may not be feasible due to cost constrains, a cheaper option is to monitor the water levels in the stream accurately and subsequently develop a rating curve for that section after carrying out a detailed survey of the crosssection at the site, applying open channel flow theory and conducting flow velocity transects at different discharges. It must be noted that the cross-section must not change with time, for the integrity of the developed rating curve to hold. In the Ngerengere catchment monitoring network, floaters with encoder together with data loggers were installed (OTT
Thalimedes). The system was calibrated by based on installed manual gauges. In addition, manual gauges were installed to act as a back up system. The stations were visited bi-monthly to check if they were working properly. Volunteered gauge readers were engaged to read water levels from the manual gauges, simple maintenance and provide security of the
11

station. This provides as back up system and ensures quality data. Figure 6 shows an example of water level data and discharge measurement data from Utari rehabilitated gauging station. (insert figure 6)
4.5.3 Sequential discharge monitoring using Acoustic Digital Current (ADC) flow meter
Discharge monitoring using Acoustic Digital Current (ADC) meter in the Ngerengere River catchment was recoerded at
12 points in the catchment. The aim of monitoring flow rates at the new gauging stations and existing gauging stations was to develop a set of rating equations, each describing a unique stage-discharge relationship for a given range of flow depths. Apart from gauging station, sequential discharge measurements along streams were measured monthly to investigate temporal and spatial pattern of ground water – surface water exchange. Figure 7 shows some results from sequential discharge measurements in the catchment. The results suggest that the Ngerengere River is a gaining stream during this season. (insert figure 7)
4.5.4 Shallow and deep ground water monitoring
Subsurface flows constitute an important component in developing a water balance for a catchment. In particular, accumulated hill slope seepage forms a shallow groundwater table which contributes significantly to the total stream flow. It is therefore important to establish its occurrence, direction of flow and possible flow rates. The shallow groundwater in the Ngerengere catchment is monitored via 9 shallow groundwater wells, which were installed through the collaboration and participation of the local community members (Figure 4). Shallow groundwater wells were monitored by gauge readers living in proximity to these gauges. The gauge readers were trained by the project team.
Figure 8 shows example results collected by gauge readers of fluctuation of shallow groundwater levels relative to river water levels at Dibundile research station. The fluctuation pattern suggests that the river gains some water from shallow groundwater during this period. (insert figure 8)
Monitoring of deep ground water was achieved by using three existing ground water wells in the catchment. These existing three wells in the catchment, previously sunk by the local authorities, complimented and expanded the spatial coverage of monitoring deep groundwater in the catchment. The monitoring of the deep groundwater was to contribute towards closing of the gap in defining the various components of the hydrological cycle in the catchment. The continued support and collaboration with the Wami Ruvu Basin Water Office facilitated a sustainable monitoring program of the groundwater in the catchment.
12

4.5.5 Soil profiling and measuring soil hydraulic properties in hydro-plots
4.5.5.1 Soil profile pits
Ten soil profile pits were dug in the hydro-plots. The pits were dug by local communities under the supervision of the experts. Experts from SUA were involved in sampling and classifying the soils based on standard methods (FAO, 1998).
Samples for quantifying soil hydraulic properties were taken from these pits.
4.5.5.2 Soil profiling
Ongoing monitoring of the volumetric soil moisture in the catchment was implemented using a Time Domain
Reflectometry (TDR) method. This involved inserting a Diviner probe into 60 mm access tubes, inserted into the soil profile to convenient depths and taking volumetric soil moisture content readings at different depths. Six access tubes of different depths ranging from 1.2 m to 1.5 m were inserted in 6 hydro-plots in catchment. The access tubes were inserted in the hydro plots under different land-use types particularly representative natural vegetation types. A bi-monthly monitoring exercise for volumetric soil moisture content in the catchment was then established where readings were taken at 10 cm intervals in all access tubes. The bi-monthly soil moisture data was complimented with data from sensors, where a nest of three sensors were installed in agro-ecosystem and agro-forestry plots in the catchment attached to data loggers. These sensors and data loggers provided a continuous and indirect measurement of soil moisture after a calibration exercise, which entailed subjecting the sensors to known soil moisture conditions.
4.5.5.3 Quantifying hydraulic soil properties
For quantifying soil hydraulic properties, we used simplified evaporation method (Schindler and Müller, 2006). The method uses the HYPROP system which involves installation of two tensiometers in a soil sample of 250 mm 3 at depths of 1.5 and 4.5 cm from the surface area, respectively. Detailed description of the method is given in Schindler and
Müller, (2006). Interesting was that different stakeholders had a keen interest in the method. SUA experts assisted in setting up the HYPROP system in soil science laboratory. Figure 9 shows example results of hydraulic conductivity function and water retention function of a sandy loam soil measured by the system. (insert figure 9)
4.6 Step 6: Feedback mechanism
A participatory learning process must involve a feedback mechanism where continuous updating and response are integrated in the learning process. Such feedback mechanisms should accommodate as much as possible, the opinions
13

and ideas from the various stakeholders. In the Ngerengere catchment, stakeholders were continuously updated on the progress of data collection. Monthly field visits and meetings were conducted to collect data and get feedback from stakeholders collecting data. These visits proved to be a useful platform for the researchers, for dialogue with stakeholders. From these updates respective stakeholders obtained an insight of some hydrological processes of the catchment. Currently, the ReACCT project continued to benefit and enjoy the support of the key stakeholders in the catchment.
5.0
Discussion
The benefits of this approach compared to conventional narrow scientific/technical approach have been shown in a number of ways. First, the participatory approach helped in identifying best sites for the instruments (Figure 3). The siting of the instruments and design of the gauging structures in the catchment involved the integration of expert knowledge, local knowledge, scientific and engineering techniques. In particular, expert knowledge (analysis of existing data, field surveys) and the local knowledge on the dominant hydrological processes, historical peak flows, flood prone areas, indicators of shallow groundwater tree species, was vital during the siting, design and construction the monitoring network. It was interesting to note expert opinion regarding the location of the new location were in most cases in agreement with key stakeholders opinion.
Second, the integrated participatory approach has proved to be effective in establishing a hydrological monitoring network and in monitoring. The approach has several benefits. Researchers were able to gain rapid insight into the hydrology of the catchment through interaction with key stakeholders. Interactions of experts and key stakeholders helped to create a conducive environment for exchange of knowledge. This helped to instill trust and in turn goodwill of the community to safeguard any installations in the area. Several smallholder farmers in the community volunteered to participate in various research activities including managing hydro-experimental trials, collecting data from the instruments and providing security. The voluntary monitoring in the catchment was beneficial in minimizing costs for monitoring.
The Ngerengere catchment hydrological monitoring network is now used to monitor different hydrological processes such as climatic parameters (rainfall, temperature, relative humidity, solar radiation and wind speed) (Figure 5); discharge (Figure 6 & 7); surface and ground water interactions (Figure 8) as well as key vegetation and soil parameters.
14

The scientific methods applied have proved simple yet effective and yielding good results. For instance, discharge monitoring methods implemented using this network can be used to improve existing data. In Ngerengere catchment, most rating curves were developed in the 1980s. In open channels it is necessary to periodically update these curves due to period changes in channel geomorphology. The sequential discharge measurements at gauging stations implemented in this monitoring system will help to develop better rating curves for different water stages which can improve the existing data. The Hyprop system has proved to be an effective method for rapid determination of soil hydraulic properties.
The process of establishing the Ngerengere catchment monitoring network has helped the experts and the stakeholders to gain insight of some hydrological processes. For example sequential discharge measurements during the peak of the rainy season suggest that the river is a gaining stream, suggesting groundwater contribution to the stream (Figure 7).
Shallow ground water levels (Figure 8) suggest a closer interaction of discharge and shallow groundwater in the flood plains. Vegetation parameters and hydrologic soil properties provides a good insight of the vegetation and soil characteristics of this study area. This information can be integrated further into models and can be applied in impact assessment studies such as investigating impacts of climate and land-use change on hydrological cycle in the region.
Considering these advantages we argue that such monitoring networks can effectively and efficiently help to build database of key hydrological processes within a given catchment. This can in turn lead to improved understanding of the key processes. However, improved understanding should be based on robust analysis of the existing data and models have recently proved to be the ideal tools for this. These networks can therefore facilitate application of models particularly data scarce environments such as our case study area. The integrated participatory approach in catchment monitoring should therefore be encouraged at all times.
However, use of this approach can be time demanding requiring expertise for its implementation and support. In particular, adequate awareness and strong institutional support are essential at all relevant levels of implementation.
Participatory processes can be biased if the representation and influence of competing groups is unbalanced, and there is risk that undue emphasis is given to conflicts that are difficult to resolve. Participation and local knowledge can be of great value, but needs to be complemented with rigorous technical assessment where this is necessary.
15

6.0
Conclusion
The paper has illustrated how an integrated participatory approach worked in establishing hydrological monitoring network in a tropical African catchment using an example of Ngerengere catchment in Upper Ruvu Sub-Basin, Tanzania.
Experience gained in applying the approach in establishing Ngerengere catchment monitoring network, suggests that the integrated participatory approach helps to assimilate local and expert knowledge in catchments monitoring which consequently results in: (i) identifying best sites for the hydrologic monitoring; (ii) instilling the sense of ownership; (iii) providing security of the installed network and (iv) minimize costs for installation and monitoring. The monitoring network is now used for monitoring the hydro-climatological processes of the catchment; has helped to build capacity of stakeholders particular Wami Ruvu Basin Water Office to monitor water resources in catchment in collaboration with other key stakeholders. In addition the network provides an opportunity for future research considering the fact that it comprises several permanent structures. The integrated participatory approach in catchment monitoring should therefore be encouraged at all times.
Finally, as with any pragmatic approach, it is sure to be partial. Significant revisions to our approach will likely be necessary in the future, as we learn by doing. In particular, we base the approach by building on existing networks and systems of governance to complement with the existing systems. As it stands, the framework is probably limited to areas similar to our study region. We maintain, however, that the issues we raise are even more salient in the context of other regions, and so we offer this as a foundation on which to build.
7.0
Acknowledgement
The work reported here was undertaken as part of the Resilient agro-lanscapes to Climate Change in Tanzania (ReaCCT)
Project funded by the Bundesministerium für Wirtschaftliche Zusammenarbeit und Entwicklung (BMZ) and Deutsche
Gesellschaft für Technische Zusammenarbeit (GTZ) under a Research Program: “Adaptation of African Agriculture to
Climate Change’’. The authors are grateful for the goodwill and support from the Wami Ruvu Basin Water Office, SUA experts and communities in Ngerengere catchment and various reviewers of this paper.
16