Critical View of Overland Flow Estimation in Semi-arid Catchments Under Land Subsidence with Long-term Field Measurements

An investigation is presented in this paper to predict Overland Flows (OF) from Rain-Falls (RF) and a set of covariates in semi-arid catchments. The study area comprises 8 catchments in the basin of Lake Urmia and its vicinity, where the catchments are at risk of land subsidence through mismanagement triggered by groundwater over-abstraction but received wisdom often implicates the problems with climate change. The paper presents a new perspective, where land subsidence by over-abstraction can impact OF regimes and thereby infiltration regimes. A strategy is formulated at three levels to abstract information from the data/results. At innovative Level 1, the research direction is scoped critically and referenced with reality. At Level 2, modelling results are catered for to be fit-for-purpose. At Level 3, the data/results are critically examined for learning. The data/results are found consistent with the observed reality that (i) a fit-for-purpose OF predictive model can be derived in terms of RF and covariates; (ii) indirect evidence reveals flow regimes of infiltration (interflow and percolation), OF and groundwater are altering, such that percolation is likely to decline and undermine aquifer replenishment regimes when exposed to subsidence risk with subsequent permanent damage. This makes a case for research, effective planning and sustainable drainage systems.