Investigation of Groundwater Logging for Possible Changes in Recharge Boundaries and Conditions in the City of Aswan, Egypt

Groundwater flow in saturated riparian buffers and implications for nitrate removal

A saturated riparian buffer (SRB) is an edge-of-field conservation practice that intercepts tile drainage and reduces nitrate flux to nearby streams by redistributing the flow as shallow groundwater. In this study, a three-dimensional, finite-difference groundwater model representative of SRBs in central Iowa was developed to assess the flow of groundwater and implications for nitrate removal during spring conditions, when flow to the SRB is highest. The model reproduces field observations of water level with Nash-Sutcliffe efficiency of 0.68, which is deemed acceptable for hydrologic models. The modeling shows that groundwater flow is three-dimensional near the distribution pipe and the stream and primarily one-dimensional in the rest of the buffer. The path the water takes in flowing toward the stream depends on where it exits the distribution pipe. When nitrate is not limiting, the potential for nitrate removal depends on the length of the path-and thus travel time-and depth because denitrification potential varies with depth. Travel time T_t can be estimated well with slight modifications to a one-dimensional approximation: T_t = 1.11L_x /v_x , where L_x is the buffer width and v_x is a one-dimensional approximation of the average linear velocity of groundwater. Refining knowledge of SRB function is an important step toward enhancing design for improving water quality.

Assessing the Hazards of Groundwater Logging in Tourism Aswan City, Egypt

This paper studies the groundwater logging problem in the Quaternary aquifer in Aswan city, Upper Egypt. Groundwater levels are already very high in Aswan city, but this has not been exploited, and it causes damage to the environment and infrastructure for roads, building, and templets. Rising groundwater leads to the deterioration and poor quality of agricultural lands. The main objective of this study is to assess and investigate the main reasons for the groundwater logging in the tourist city of Aswan using field investigation during different periods and gain a better understanding of the water dynamics in the study area. This study investigated the surface water levels in the High Dam Lake (HDL), the Kima Lake water levels, the recharge in the fish hatchery, the abstraction well rates in Kima and El-Shalal, and the leakage from the drinking water and wastewater network in Aswan city within the study area using field investigation. The results of this study show that the HDL is one of the most important sources feeding the aquifer in the study area, and it affects the rise and fall of the groundwater levels, but it is not the only factor that affects this problem. Moreover, the rise in the groundwater levels was due to the infiltration from the unlinking fish hatchery, the reduction in abstraction well rates from Kima Lake, the lack of abstraction from El shallal region, the increase in the leakage from drinking water pipelines, sewage networks and septic underground wastewater tanks; these factors are affecting groundwater logging in Aswan city. Potential groundwater level maps for the study area were generated using field data and ArcGIS technique for the years 2010, 2012, 2014, 2017, 2018, and 2020. Based on the results of the potential groundwater maps, the maximum and minimum difference for the groundwater levels in the study area between 2017 and 2012 reached 12.56 m and 0.83 m, respectively; also, between 2018 and 2017, the levels were 4.34 m and 0.25 m, respectively. Moreover, between 2020 and 2018, they were 8 m and 0.38 m, respectively.