1. Raghuveer K. Vinukollu Class Term Project – GIS in Water Resources
November 30, 2004
Determination of Spatially-Distributed Crop Water Requirements at Regional Level using ArcET Utility
Raghuveer K. Vinukollu
Class Term Project – GIS in Water Resources

2. Introduction
Area: Semi-arid

3. Introduction Finite water resources
Increasing urban and industrial water demand
Decreasing agricultural supply

4. Why GIS ?
Point estimate
Regional estimate

5. Objectives
Estimate the reference ET values and the crop water requirements generated using ArcET;
Etc = ETo x Kc
Compare the regional estimates of reference ET values with those generated using soil water balance method; and,
Evaluate the reliability of ArcET for practical purposes

7. ArcET procedure
Source:

8. Data Meteorological data -- Monthly precipitation data
-- Monthly temperature data
Landuse data
-- crop distribution in the study area
DEM of the study area
Site-specific crop coefficients
Location and elevation of the meteorological stations

9. (SCS modified Blanney-Criddle eqn.)
Procedure
Pre-process
Data
ArcET
Regional ET
(Hargreaves eqn.)
Regional ET
(SCS modified Blanney-Criddle eqn.)
ETo - ER
Comparison
Crop water requirement
50, 75 and 95 % probability for non-exceedence
Climatic Scenarios

12. Discussion Design of new irrigation system Rough estimation
Usefulness
Design of new irrigation system
Rough estimation
Interpolation of temperature and precipitation using elevation
Limitation
Irrigation water management and scheduling
Soil water balance

13. Future work ArcET – More compatible versions file formats
ArcET – Soil water balance
ArcET – Cell by cell computation of IWR

14. Acknowledgements Daniele Zaccaria Shujun Li