Abstract: Qanat is a type of drain that extract water from aquifers by gravity. Significant amount of fresh water used in Middle East and other parts of the world are supplied by qanats. Despite their importance, discharge variation of these type of wells received almost no attention. The aim of this research is to obtain a Laplace domain solution of discharge variation of a qanat installed in an anisotropic unconfined aquifer subjected to arbitrary areal recharge and nearby pumping well(s) discharge. A new semi-analytical solution of drawdown is obtained first to implement the effects of arbitrary areal recharge and nearby pumping well(s) using the principle of superposition. Then, the discharge variation solution of the qanat is obtained from the drawdown solution. To establish a constant-head boundary condition at the qanat periphery, the qanat is discretized into several segments. The results of this study are presented in dimensionless discharge-dimensionless time curves. The effects of hydraulic as well as geometric parameters on the discharge variation of the qanat due to arbitrary areal recharge, falling of water table from its initial position and discharge of nearby wells are explored. We also investigate the influences of distance and screen depth and location of the nearby well on the discharge variation of the qanat. The results of this study can be utilized for multiple purposes: 1) to predict discharge of qanat in response to rainfall and nearby pumping well(s); 2) to estimate the aquifer parameters using hydrograph of the qanat; 3) to determine optimal location and pumping pattern of the nearby wells to minimize their influences on the discharge of the qanat; 4) to calculate water budget of aquifers drained by a qanat. The equation presented in this work can also be used to estimate discharge of a horizontal drain installed in cropland subjected to arbitrary irrigation pattern.

Abstract: The city of Alcudia de Crespins, in the centre of the Valencia province (east of Spain), has an exceptional water distribution system that in the past served fresh water to many houses in the town. This system is formed by more than one km of tunnels and underground cisterns, and dates probably in the late medieval times, while it has been in use and suffering modifications until 1955. This paper presents the structure and characteristics of such exceptional system, and explains the functioning parameters of the infrastructure.

Abstract: With its arid and semi-arid climate, Iran claims about one-third of the world’s average annual precipitation. Accordingly, the present study investigated whether an effective water resources management (WRM) strategy (both groundwater and reservoir resources) could reduce groundwater drawdown while simultaneously providing secure enough water for preservation of agricultural activities and rural settlements. For this purpose, a comprehensive system dynamics (SD) model incorporating reservoir, surface-water, and groundwater resources was developed. Then, the model was implemented for the Nesa plain in Bam County, Iran, as an example. In this plain, the construction of a dam to supply drinking water to the cities of Bam and the Bam Industrial Zone had devastated the environment and human communities in the downstream areas, leading to the depopulation of as many as 104 villages in the Bam region. The results of the SD model revealed that the artificial recharge of the plain groundwater aquifer along with the management of the operation of the wells and increasing productivity would be very effective. In order to estimate future precipitation data, the SDSM statistical exponential microscale model was used to microscale the large CanESM2 scale model under two scenarios of RCP4.5 and RCP8.5. The continuation of the current trend of the groundwater resources in the plain during the next 20 years will also cause a drop in water level of 8.3 m compared with the existing situation and a reduction of 41 m compared with the long-term average of 1980. Based on this modeling effort, upon releasing 60% of river flow, surplus to downstream demand, for recharging aquifer through artificial recharge projects, the rate of water table fall will decline significantly over a 20-year period and the amount of negative aquifer water balance would most likely improve from 65.5 to 35.17 million cubic meters annually.