Annual Runoff and Sediment in Duhok Reservoir Watershed Using SWAT and WEPP Models

Estimation of runoff volume and sediment load is the main problem that affects the performance of dams due to the reduction in the storage capacity of their reservoirs and their effect on dam efficiency and operation schedule. The simulation models can be considered for this purpose if the continuous field measurements are not available. Soil and Water Assessment Tool (SWAT) and Water Erosion Prediction Project (WEPP) models were applied to estimate the annual runoff volume and sediment load for Duhok Dam Reservoir in north of Duhok/Iraq for the period 1988-2011. The estimated annual runoff volume varied from 2.3 to 34.7 MCM for considered period. Those values were affected by rainfall depth, intensity and runoff coefficient. The resultant annual runoff coefficient for the studied area ranged from 0.05 to 0.35 (average was 0.18) causing an average runoff volume of about 14 MCM. The results of sediment routing indicated that the values of sediment yields varied from 50 to 1400 t/km2/year depending on sub basin properties. The average annual sediment load from the whole watershed is about 120 × 103 ton. The estimated total sediment arrived to Duhok Reservoir for the considered period 1988-2011 was about 2.9 × 106 ton. The results indicate that both models gave reasonable results in comparison with measured values. Based on statistical criteria, the results of both models are close to gather.

Expected Future of Water Resources within Tigris-Euphrates Rivers Basin,Iraq

Iraq is one of the riparian countries within basins of Tigris-Euphrates Rivers in the Middle East region. The region is currently facing water shortage problems due to the increase of the demand and climate changes. In the present study, average monthly water flow measurements for 15 stream flow gaging stations within basins of these rivers in Iraq with population growth rate data in some of its part were used to evaluate the reality of the current situation and future challenges of water availability and demand in Iraq. The results showed that Iraq receives annually 70.92 km3 of water 45.4 and 25.52 km3 from River Tigris and Euphrates respectively. An amount of 18.04 km3 of the Tigris water comes from Turkey while 27.36 km3 is supplied by its tributaries inside Iraq. The whole amount of water in the Euphrates Rivers comes outside the Iraqi borders. Annual decrease of the water inflow is 0.1335 km3·year-1 for Tigris and 0.245 km3·year-1 for Euphrates. This implies that the annual percentage reduction of inflow rates for the two rivers is 0.294% and 0.960%, respectively. Iraq consumes annually 88.89% (63.05 km3) of incoming water from the two rivers, where about 60.43% and 39.57% are from Rivers Tigris and Euphrates respectively. Water demand increases annually by 1.002 km3, of which 0.5271 km3 and 0.475 km3 are within Tigris and Euphrates basins respectively. The average water demand in 2020 will increase to 42.844 km3·year-1 for Tigris basin and for Euphrates 29.225 km3·year-1 (total 72.069 km3·year-1), while water availability will decrease to 63.46 km3·year-1. This means that the overall water shortage will be restricted to 8.61 km3.

A GIS-based approach for identifying potential sites for harvesting rainwater in the Western Desert of Iraq

People living in arid and semi-arid areas with highly variable rainfall and unforeseeable periods of droughts or floods are severely affected by water shortages and often have insecure livelihoods. The construction of dams in wadies to harvest rainwater from small watersheds and to induce artificial groundwater recharge is one of the solutions available to overcome water shortages in the Western Desert of Iraq. The success of rainwater harvesting (RWH) systems depends heavily on their technical design and on the identification of suitable sites. Our main goal was to identify suitable sites for dams using a suitability model created with ModelBuilder in ArcGIS 10.2. The model combined various biophysical factors: slope, runoff depth, land use, soil texture, and stream order. The suitability map should be useful to hydrologists, decision-makers, and planners for quickly identifying areas with the highest potential for harvesting rainwater. The implementation of this method should also support any policy shifts towards the widespread adoption of RWH.