1. Water Balance Estimation 1 Naomi Radke, seecon international GmbH

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3. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Contents 1.What is a Water Balance Estimation 2.Who is Involved? 3.What Can it be Used for? 4.Uncertainty and Problems 5.Conducting a Water Balance Estimation 6.Applicability 7.Advantages and Disadvantages 8.References 3

4. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info A water balance estimation is...... A tool to assess the current status and trends in water resources availability in an area over a specific period of time. 4 1. What is a Water Balance Estimation? Change in global water availability. A water balance estimate can reveal the situation of water availability. Source: UNEP GRID-A (2009)

5. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Calculating the water balance The simplest form of water balance estimation is: P = Q + E ± ∆S 5 1. What is a Water Balance Estimation? P: Precipitation Q: Runoff E: Evaporation ∆S:Storage in the soil, aquifers or reservoirs Example of water balance estimation. Source: BGR (2008)

6. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Conservation of water...... If in a specific area over a specific time water inflows = water outflows ± changes in storage 6 1. What is a Water Balance Estimation? Precipitation (rainwater) is either transferred to surface run off or evaporates OR it is stored in the ground.

7. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Stakeholders involved in decision-making that require more detailed info on water available Specialists or staff that have undergone training and access to specialist support 7 2. Who is Involved? RiverWare (a river system modelling tool)Training in Mexico. Source: Water Balance Consulting (2013).

8. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Asses the current status and trends in water resource availability in an area over a specific period of time Strengthen water management decision-making by assessing and improving the validity of visions, scenarios and strategies 8 3. What Can it be Used for? Managing aquifer recharge/discharge. Source: FAO et al. (2012)

9. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Uncertainty in water balance estimation There is always uncertainty due to inadequate capture networks, measurement errors, complex spatial and temporal heterogeneity of hydrological processes Uncertainty Analysis is an important part of water balance estimation! 9 4. Uncertainty and Problems

10. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Problems occurring in water balance estimation Temporal and spatial boundaries are not defined Quality of input data is poor Double counting of water flows when water flows within an area added to water flow of exiting area Inappropriate extrapolation of field level information to a larger scale Intuition (often based on popular myths) is used rather than good quality information. The storage term(s) of the water balance is omitted Political or other pressures result in unreliable estimates that have been manipulated 10 4. Uncertainty and Problems

11. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Materials and Resources Techniques: From very simple “back of the envelope” calculations to highly complex computer-based models Precondition: Sound knowledge of hydrological processes Advisable o To contract specialist service o To have access to a quality-controlled information database 11 5. Conducting a Water Balance Estimation

12. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Methods (1/2) Step1: Define boundaries of the area of interest Step 2: Undertake a needs assessment of the water balance information that is required among stakeholders. Define water balance components of particular interest Step 3: Produce a simply schematic diagram that shows storage, inflows and outflows from the area of interest Step 4: Identify a source(s) of quality-controlled info, relevant for area and period 12 5. Conducting a Water Balance Estimation

13. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Methods (2/2) Step 5: Uncertainty and sensitivity analysis on this info. If inadequacies, redefine the boundaries and/or modify equation Step 6: Produce water balance estimates in a format that is useful for visioning, scenario building and planning with the community Step 7: Control these estimates regarding their quality before they are disseminated Step 8: Disseminate findings to stakeholders in a form they can understand 13 5. Conducting a Water Balance Estimation

14. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Result Example 14 5. Conducting a Water Balance Estimation Australian water balance report. Source: NWC (2005)

15. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info Water balance estimation as basis for... Quantitative evaluation of water resources and their change under human activities Hydrological substantiation of projects for the rational use, control and redistribution of water resources in time and space 15 6. Applicability How does irrigation effect the water availability? A water balance estimation can help assess the severity of human impact on the water cycle. Source: B. Haas

16. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info 16 7. Advantages and Disadvantages Advantages: Provides you with a comprehensive understanding of the water flow system and water resources in your area Disadvantages: Often incorrect for the many reasons listed before Often, minimal or no account is taken of uncertainty when estimates are made and presented Very complex work process that needs to be done by qualified experts (at least as support) which requires considerable time and resources

17. Water Balance Estimation Find this presentation and more on www.sswm.infowww.sswm.info BGR (2008): Water Cycle/Water Balance for Germany. Hannover: Bundesanstalt fuer Geowissenschaften und Rohstoffe (BGR). URL: http://www.bgr.bund.de/EN/Themen/Wasser/Bilder/Was_wasser_startseite_wasserkreis_g_en.html [Accessed: 14.10.2013] http://www.bgr.bund.de/EN/Themen/Wasser/Bilder/Was_wasser_startseite_wasserkreis_g_en.html Water Balance Consulting (2013): RiverWare Simulation Training in Mexico. Boulder: Water Balance Consulting. URL: http://waterbalance.org/projects-page/riverwaretraining/ [Accessed: 14.10.2013]http://waterbalance.org/projects-page/riverwaretraining/ FAO, GEF, IAH, IHP, World Bank (2012): Management of aquifer recharge and discharge processes and aquifer storage equilibrium. Rome: FAO. URL: http://www.zaragoza.es/ciudad/medioambiente/onu/en/detallePer_Onu?id=587 [Accessed: 14.10.2013] http://www.zaragoza.es/ciudad/medioambiente/onu/en/detallePer_Onu?id=587 NWC (Editor) (2005): Australian Water Resources 2005 - Water Balance Assessment. Canberra: Australian Government, National Water Commission (NWC). URL: http://www.water.gov.au/WaterAvailability/Waterbalanceassessments/index.aspx?Menu=Level1_3_2 [Accessed: 14.10.2013] http://www.water.gov.au/WaterAvailability/Waterbalanceassessments/index.aspx?Menu=Level1_3_2 UNEP GRID-A (2009): The Contribution of Climate Change to Declining Water Availability. Arendal: United Nations Environment Programme (UNEP) GRID Arendal. URL: http://maps.grida.no/go/graphic/the-contribution-of-climate-change-to-declining-water-availability [Accessed: 14.10.2013] http://maps.grida.no/go/graphic/the-contribution-of-climate-change-to-declining-water-availability 17 8. References

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