The check of elevation data is an essential step prior the start of any drainage study. An investigation for this concept was done in Lagos, Nigeria using two types of survey sources; a Digital Elevation Model (DEM) with a 15 m resolution produced from Russian Stereo Satellite images (RSS) and a LiDAR survey with a 5 m DEM resolution. A comparison between the RSS model survey and the LiDAR survey showed that LiDAR survey was more accurate than RSS survey and given high reliability. The study also showed that RSS survey could sometimes become misleading and could not assure reliability. A watershed modeling tool was used to analyze both surveys to produce the expected drainage streams. It was found that some locations using RSS had a false drainage direction when compared with higher accurate LiDAR surveys.

Simulations using the Crop Water and Irrigation Requirements model (CROPWAT), show that the projected climatic changes over the period from 2026 to 2050 in the Yanyun irrigation district, Yangzhou, China, will cause the paddy lands there to lose about 12.4% to 37.4%, and 1.6% to 45.6%, of their future seasonal rainwater in runoff under the Representative Concentration Pathways (RCP45 and RCP85), respectively. This may increase future irrigation requirements (IRs), alongside threatening the quality of adjacent water bodies. The CROPWAT simulations were re-run after increasing the Surface Storage Capacity (SSC) of the land by 50% and 100% of its baseline value. The results state that future rainwater runoff will be reduced by up to 76% and 100%, and 53% and 100% when the SSC is increased by 50% and 100%, under RCP45 and RCP85, respectively. This mitigates the future increase in IRs (e.g., under RCP45, up to about 11% and 16% of future IRs will be saved when increasing the SSC by 50% and 100%, respectively), thus saving the adjacent water bodies from the contaminated runoff from these lands. Adjusting the SSC of farmlands is an easy physical approach that can be practiced by farmers, and therefore educating them on how to follow up the rainfall forecast and then adjust the level of their farmlands’ boundaries according to these forecasts may help in the self-adaptation of vast areas of farmlands to climate change. These findings will help water users conserve agricultural water resources (by mitigating the future increase in IRs) alongside ensuring better quality for adjacent water bodies (by decreasing future runoff from these farmlands). Increasing farmers’ awareness, an underutilized approach, is a potential tool for ensuring improved agricultural circumstances amid projected climate changes and preserving the available water resources.

In this study, in the context of climate change simulation models were employed to compute the reference evapotranspiration (ETo), net irrigation water requirement (NIWR) and design a new sprinkler irrigation system for two arid sites (Siwa Oasis and West Elminya fields) inside the 1.5-million acres reclamation project in the Egyptian western desert. The CROPWAT 8 model was used to compute NIWR and the irrigation schedule for the main crops wheat, barley, maize, sugar beet, potato, tomato, and date palm, five scenarios were employed the current (1991-2022) scenario, representative concentration path (RCP) 8.5 greenhouse gas emission for the 2040s, 2060s, 2080s, and 2100s scenarios, corresponding to 1.6, 2.1, 3.3, and 4.4 oC expansion with respect to the current baseline 1991-2022. The WaterGEMS model was utilized to run long-term simulations of hydraulic behavior within pressurized pipe networks to irrigate 43 acres using deep groundwater well. ETo values for the current scenario show 4.56 and 5.7 mm for the Siwa Oasis and West Elminya fields respectively. The climate changes cause an increase of the ETo by 4.6, 5.9, 9.4, and 12.7% for RCP: 8.5 greenhouse gas emissions for the 2040s, 2060s, 2080s, and 2100s scenarios respectively for the Siwa Oasis field. On the other hand, an increased ratio for the ETo by 4.2, 5.4, 8.6, and 11.6% for the West Elminya field respectively. The designed sprinkler system indicated a capacity of 111.4 m3 h-1 and 167 m3 h-1 for Siwa and West Elminya fields, respectively. The study suggests the application of modern irrigation systems and crop patterns for wheat, barley, potato, and sugar beet to save irrigation water.