Farm Irrigation Water Saving in the Upper Yellow RiverBasin: Application to Huinong Irrigation District,Ningxia

摘要

Excess irrigation water applied for both upland and rice crops, combined with poormanagement of the supply and distribution systems, cause important problems of waterlogging andsalinity in the upper reaches of the Yellow River basin, namely in the Ningxia Province, China. Tohelp controlling such problems, improved farm irrigation systems and scheduling may play animportant role but main impacts shall result from changing water allocation to the Hetao irrigationsupply canals. The irrigation scheduling simulation model ISAREG was used for the upland cropsbecause it is able to accurately compute the capillary rise from the water table and the deeppercolation when excess water is applied. The model has been previously calibrated and validatedfor North China, and was explored with meteorological, crop and soil data collected in the HuinongIrrigation District. Surface irrigation for upland crops was evaluated in farmers fields and observationswere used to parameterize the simulation models SRFR and SIRMOD. The models ISAREG andSRFR or SIRMOD were explored interactively in such a way that surface irrigation simulationscorrespond to the application of required water depths at the most convenient timings and thatirrigation scheduling simulations take into consideration the limitations imposed by the basin systems.Results show that, at present, a very large part of the applied and infiltrated depths percolates to thewater table, 63 % in average. When an improved water-table depth would be maintained andirrigation systems and scheduling would be improved, seasonal irrigation could be reduced by aboutone third and percolation to near 15 % of volumes applied. When precise leveling would also beimplemented, excess percolation could be avoided.