Climate and hydrological conditions in any hydrological basin are multi-combined reflection of natural factors of morphology and soil nature, as well as the changing in climate factors that affect directly the hydrological cycle. The water balance equation for any natural area or water body indicates the relative values of inflow, outflow, and change in water storage for the area or water body. Estimation of water surplus and natural groundwater recharge in Iraq depending on water balance equation and meteorological data was the aim of this research. Corrected potential evapotranspiration were compared with annual and monthly rainfall in (32) meteorological stations to obtain actual evapotranspiration using water balance equation. Water surplus was divided into runoff and natural groundwater recharge where runoff coefficient method was used to estimate runoff. The obtained mathematical relationship between rainfall with both water surplus and actual evapotranspiration can be used to estimate these two parameters directly from rainfall. The results indicate that water surplus increased toward northeast direction of Iraq, while the minimum values of runoff and groundwater recharge located in western desert of Iraq. The climate conditions of desert were the major influence on reducing rainfall and rising temperature resulting decreasing water surplus, runoff, and groundwater recharge.

中文翻译：

---

推导数学方程式以估算伊拉克的剩余水量和地下水补给量

任何水文盆地的气候和水文条件都是形态和土壤自然因素的综合反映，以及直接影响水文循环的气候因素的变化。任何自然区域或水体的水平衡方程式表示该区域或水体的流入，流出和储水量变化的相对值。本研究的目的是根据水平衡方程和气象数据估算伊拉克的水资源过剩和天然地下水补给量。将校正后的潜在蒸散量与（32）个气象站的年和月降水量进行比较，以使用水平衡方程式获得实际的蒸散量。剩余水分为径流和天然地下水补给，其中径流系数法用于估算径流。所获得的降雨与水盈量和实际蒸散量之间的数学关系可用于直接根据降雨估算这两个参数。结果表明，剩余水量向伊拉克东北方向增加，而径流和地下水补给量的最小值位于伊拉克西部沙漠。沙漠的气候条件是减少降雨和增加气温的主要影响因素，从而导致水资源过剩，径流和地下水补给减少。结果表明，剩余水量向伊拉克东北方向增加，而径流和地下水补给量的最小值位于伊拉克西部沙漠。沙漠的气候条件是造成降雨减少和温度升高的主要因素，从而导致水资源过剩，径流和地下水补给减少。结果表明，剩余水量向伊拉克东北方向增加，而径流和地下水补给量的最小值位于伊拉克西部沙漠。沙漠的气候条件是减少降雨和增加气温的主要影响因素，从而导致水资源过剩，径流和地下水补给减少。