Physical & Quality Groundwater Monitoring
Information for effective management
Groundwater Management for
Hygiene and Sanitation
IWSD – Harare June 2011
GROUNDWATER STATUS QUO
Millions
100’s
of m3 pumped every year: Monitored? Who? How?
of thousands of users: Registered? Controlled?
10’s
of thousands of wells/boreholes: Registered? Maintained?
Info. about location, abstraction levels, water levels, water
quality, formation, etc –
1000’s
of sources of pollution: Location, nature & quantity of
pollutants? aquifer vulnerability?
Many
governing departments/institutions: Joint management ?
Coordination / cooperation?
MONITORING: WHO?
• Who requires/requests for monitoring?
• Who determines priorities and expected outcomes?
• Who pays?
• Who implements the monitoring?
• Who owns/ shares the data?
GROUNDWATER USE AND QUALITY MONITORING
• Principles of groundwater monitoring
• Monitoring cycle and tools
• Monitoring resource use and aquifer response
• Groundwater quality monitoring
• Effectiveness, cost and quality control
• Examples
WHAT IS MONITORING NOT?
PROVIDING IRRELEVANT INFORMATION TO ILL DEFINED QUESTIONS
WHAT IS GROUNDWATER MONITORING?
Groundwater monitoring comprises the
collection, analysis and storage of data on a
regular basis to provide information for
effective groundwater management to a
variety of stakeholders.
Monitoring makes groundwater visible, if…….
GROUNDWATER MONITORING SYSTEMS BY FUNCTION
SYSTEM
Primary
(Reference)
Secondary
(Early
warning
Protection )
Tertiary
(Pollution
impacts)
BASIC FUNCTION
evaluation of general groundwater
behaviour, e.g.: trends(variation in land use)
and processes (recharge)
protection against potential impacts to:
well-fields/springheads for public WS
urban infrastructure (land subsidence)
archaeological sites against rising WT
groundwater-dependent ecosystems
early warning of groundwater impacts from:
• diffuse sources (intensive agr. land use)
• point sources (industrial sites etc)
Compliance Complying to requirements in a permit
(abstraction rates, quality changes, water
(management
level decline)
)
WELL
LOCATIONS
in areas with
uniform
hydrogeology
and land use.
around
facilities/areas/
features requiring
Protection.
immediately down +
up-gradient from
hazard
Around groundwater
well fields
PURPOSE AND FUNCTION OF MONITORING
Pollution source
Impact monitoring
Object of protection
Early warning
Impacts
Risks
Risks
Impacts
Trend monitoring
Groundwater abstraction
Compliance /management + early warning monitoring
Groundwater is invisible
RECHARGE ESTIMATES MAPUTO
Maputo 1984
Recharge estimations
So = 40 mm
Rainfall: 800-850 mm/year
Recharge: 165-185 mm/year
MONITORING: DIFFERENT PURPOSE <> SAME DATA
Monitoring for well field operaton
Well field operation
Drinking water
Irrigation water
Monitoring
Industrial
Monitoring well
- daily abstraction / pumping hours
- well performance
- water level fluctuations
- water quality for purpose of use
Monitoring for resource mgt.
Monitoring
- allocation / abstraction control
- quality /pollution control
- environmental flows
- information sharing/ knowledge dev.
- awareness /demand mgt.
- linkage with other planning sectors.
WHY IS GROUNDWATER MONITORING IMPORTANT?
Groundwater is a hidden resource to which we have no
direct access
Contrary to surface water, changes in groundwater quality
and quantity are slow processes which cannot be
determined by snap shot monitoring
Changes in groundwater quality are often irreversible
GROUNDWATER USE AND QUALITY MONITORING
• Principles of groundwater monitoring
• Monitoring cycle
• Monitoring resource use and aquifer response
• Groundwater quality monitoring
• Effectiveness, cost and quality control
• Examples
THE MONITORING CYCLE
Management question and
monitoring objectives
• Trends and changes
• Impacts and risks
• Compliance
Definition of information
needs
Collection of static and
dynamic data
• Groundwater specific
• Water use
• Supporting data
Data storage, interpretation
and dissemination
Management information
and actions
Information > data > information
WHAT DATA DO WE COLLECT?
Static data
(design phase, reference)
Type of data
Groundwater
specific data
Water use
Supporting
data
- existing data on grw. levels
-
existing data on grw. quality
tests on existing wells
information from new wells
aquifers tests
Dynamic data
(monitoring changes)
- monitoring observation
wells (levels and quality)
- monitoring existing wells
- monitoring springs
- population registers
- water use inventories
- demographic changes
- monitoring water use
-
- surface water monitoring
- rainfall /climate data
- changes in land use
surface water / springs
climate data
land use data
geological data (existing wells)
HOW DO WE MONITOR ?
• Monitoring networks
•
•
•
•
Network density (hydrogeological and hydro-chemical
heterogeneity/complexity)
Location observation points (existing used wells, abandoned
wells, new observation wells, climate, surface water, water
use)
Monitoring parameters
Measuring and sampling frequency (instruments, budget,
monitoring program)
• Satellite images and airborne surveys
• Statistics
Factors determining design
• Budget,
• Monitoring objectives
MONITORING POINTS
Groundwater
Wadi Flows
Water use
Climate
River water
GROUNDWATER USE AND QUALITY MONITORING
• Principles of groundwater monitoring
• Monitoring cycle and tools
• Monitoring resource use and aquifer response
• Groundwater quality monitoring
• Effectiveness, cost and quality control
• Examples
AQUIFER REPONSE: WATER LEVELS
Example: Water saving to reduce aquifer depletion
•Historic data
•Baseline data
(reference)
•Monitoring data
MONITORING FOR RESOURCE USE & AQUIFER RESPONSE
Monitoring of groundwater levels and groundwater use is
needed to verify the predicted aquifer response for
management scenarios.
Important issues:
•knowledge of the reference situation: historic and baseline data
•groundwater flow is related to the groundwater levels
•water level response is related to the use
But:
There remains always a certain uncertainty
HYDROGRAPHS: NYAMANDLOVU SST AQUIFER
Nyamandlovu SST Aquifer: BH Umgu-093 Hydrograph
1130.00
Water Level Altitude (m)
1128.00
1126.00
1124.00
1122.00
1120.00
1118.00
1116.00
1114.00
1112.00
1110.00
01/1989
Sep-90
May-92
Jan-94
Sep-95
Year
May-97
Jan-99
Sep-00
MONITORING GROUNDWATER USE
•Direct monitoring
- metering and regular inspection
•Indirect monitoring
-
energy consumption and average pumping rates
pumping hours and average pumping rate
population estimates and random tests (drinking water)
use of remote sensing information (irrigation water use)
GROUNDWATER USE AND QUALITY MONITORING
• Principles of groundwater monitoring
• Monitoring cycle and
• Monitoring resource use and aquifer response
• Groundwater quality monitoring
• Effectiveness, cost and quality control
• Examples
MONITORING FOR GROUNDWATER QUALITY
Sampling of production wells
• cheap but often unreliable/not representative
• useful to determine the reference situation
Sampling of purpose- drilled monitoring wells:
• Reference monitoring for natural water quality /natural recharge
• Offensive monitoring of pollution sources
• Defensive monitoring for groundwater supplies
• Evaluation monitoring for sites of known aquifer contamination
MONITORING STRATEGIES
Offensive monitoring
Early detection of incipient
aquifer contamination by known
pollution sources
Defensive monitoring
Provide warning of pollution
plumes threatening potable well
fields or individual wells
WHERE TO LOCATE MONITORING POINTS ?
MONITORING FOR GROUNDWATER QUALITY
Physical parameters (indicators)
- Electric conductivity /temperature
- pH
- DO
•Manuel and automatic recorders
Water sampling and analysis
parameters selected in the light of the quality objective and
pollution hazard assessment: quality assurance and control
GROUNDWATER USE AND QUALITY MONITORING
• Principles of groundwater monitoring
• Monitoring cycle and
• Monitoring resource use and aquifer response
• Groundwater quality monitoring
• Effectiveness, cost and quality control
• Examples
HOW ARE RESPONSIBILITIES SHARED ?
Legal and regulatory basis required through water rights / water
allocation plan /permitting system etc
Typical division of responsibilities
•
National level: basic reference networks/ climate stations
•
Regional level/RBA/AMOR: regulation control + protection
•
Contractors: contractual obligation for well testing
•
Large abstractors: monitoring requirements in permit
•
Local water users: self monitoring / awareness
+ Data collected by other agencies
QUALITY ASSURANCE AND QUALITY CONTROL
Prevention (assurance) is better than cure (control)
• Starts with the observer: cross checks, keep
your eyes open
• Guidelines: follow procedures (e.g. for sampling)
• Keep copy of field readings
• QA/AC on chemical analysis
• QC procedures for data entry in MIS
• QC control in data processing
HOW ENSURE THAT MONITORING IS COST EFFECTIVE?
Monitoring is considered expensive because the return on
investment is generally not visible in the short run
• Monitoring by objectives
• Include cost-benefit analysis in project design
• Promote cost effectiveness and reliability by:
• Defining clear information needs
• Use of data already collected in other programs
• Use of existing wells (abstraction wells and abandoned wells)
• Use of indicators: water level/temperature /EC (divers)
• Promoting self monitoring and self regulation
• Effective QC and QA system
GROUNDWATER USE AND QUALITY MONITORING
• Principles of groundwater monitoring
• Monitoring cycle and
• Monitoring resource use and aquifer response
• Groundwater quality monitoring
• Effectiveness, cost and quality control
• Examples
BANGKOK: REGULATION AND GROUNDWATER FUND
-
Regulatory and economic measures
- Imposed based on monitoring information
Groundwater Abstraction Bangkok
•Tariff 3.5
Bht
2.2
Abstraction (MCM)
2
Critical zone announcement
•Tariff 8.5
Bht
1.8
1.6
Groundwater fund used for:
- Monitoring
- Research
- Training & manpower dev.
1.4
1.2
1
0.8
0.6
0.4
0.2
0
1970
1974
1978
1982
1986
1990
Year
1994
1998
2002
2006
CONCLUSION
Monitoring makes groundwater visible if it:
•
addresses well-defined management information
needs (demand driven), is
•
cost-effectively implemented providing
•
reliable information
WHAT IS THE
HEIGHT OF
THAT TOWER
IN METERS ?
I HAVE MEASURED IT
WITH TWO
DIFFERENT
MEASURING TAPES
AND THE HEIGHT IS
26 +/- 2 METERS.
Thank you
Exercise: 3 Groups
1 Monitoring a dune infiltration system to protect a drinking
water well field against seawater intrusion
2 Monitoring plan for an industrial site to prevent spreading of
possible contaminants through the groundwater
3 Monitoring system for trend monitoring in a sedimentary
shallow aquifer in river basin
Exercise: 3 Groups
• Define the monitoring objectives and basic design
parameters
• What are the main benefits and who are the main
beneficiaries of the monitoring
• Suggestions to make the monitoring plan cost effective
• How to assure sustainable financing?
• Who will implement the monitoring and how is the
monitoring information handled to address the
management objectives
HYDROCHEMISTRY: QA and QR !!!
•
•
•
•
•
•
Field measurements (EC and pH)
Sampling procedures
Ion balance
Extreme values (high and low)
Use certified labs
Contra expertise (5% of the samples)
GROUNDWATER SAMPLING