MIKE-SHE integrated groundwater and surface water model used to simulate scenario hydrology for input to DRIFT-ARID: the Mokolo River case study

Abstract

A fully integrated, physically-based MIKE SHE/MIKE11 model was developed for the Mokolo River basin flow system to simulate key hydraulic and hydrologic indicator inputs to the Downstream Response to Imposed Flow Transformation for Arid Rivers (DRIFT-ARID) decision support system (DSS). The DRIFT-ARID tool is used in this study to define environmental water requirements (EWR) for non-perennial river flow systems in South Africa to facilitate ecosystembased management of water resources as required by the National Water Act (Act No. 36 of 1998). Fifty years of distributed daily climate data (1950 to 2000) were used to calibrate the model against decades of daily discharge data at various gauges, measurements of Mokolo Dam stage levels, and one-time groundwater level measurements at hundreds of wells throughout the basin. Though the calibrated model captures much of the seasonal and post-event stream discharge response characteristics, lack of sub-daily climate and stream discharge data limits the ability to calibrate the model to event-level system response (i.e. peak flows). In addition, lack of basic subsurface hydrogeologic characterisation and transient groundwater level data limits the ability to calibrate the groundwater flow model, and therefore baseflow response, to a high level. Despite these limitations, the calibrated model was used to simulate changes in hydrologic and hydraulic indicators at five study sites within the basin for five 50-year land-use change scenarios, including a present-day (with dam), natural conditions (no development/irrigation), and conversion of present-day irrigation to game farm, mine/city expansion, and a combination of the last two. Challenges and recommendations for simulating the range of non-perennial systems are presented.

Crop Upgrading Strategies and Modelling for Rainfed Cereals in a Semi-Arid Climate—A Review

“…We found that 30 out of the 187 papers contained in this review specifically covered the modelling of at least one of the four selected UPS in semi-arid areas. One strong reason for such a shortage is the limitation in the availability of, and access to, quality data [100,143,144]. Maize was covered by 51% of the papers reviewed.…”

Accounting for flow intermittency in environmental flows design

“…The DRIFT‐ARID approach recognizes the need to represent periods of unmeasurable surface flow when groundwater dynamics become controlling. An integrated groundwater‐surface water model simulates daily groundwater depth, groundwater flow beneath the river and net groundwater baseflow to the river (Prucha et al, ). Onset dates of non‐flow and flowing periods are also new indicators that quantify the duration of unmeasurable surface flows.…”

Suitability of a Coupled Hydrologic and Hydraulic Model to Simulate Surface Water and Groundwater Hydrology in a Typical North-Eastern Germany Lowland Catchment

“…The MIKE SHE model used in this study uses the "ETRS_1989_UTM_Zone_33N_8stellen" coordinate system in metric units. The performance of the hydrological model was evaluated at different grid sizes (20,50,100,200, and 300 m) and a spatial resolution of 100 m was selected as an optimum compromise between computational time and model performance. The model area of 400 km 2 was divided into 100 × 100 m computational cells to represent the spatial variations in soil, land use, and geology.…”

“…Physically-based dynamically-coupled SW and GW hydrological models are increasingly being used to examine the environmental interactions [10], transport of solute [11], flood modelling [12], and understanding of catchment hydrology [13][14][15][16][17][18]. A good forecast of an integrated hydrological model does not only depend on the code but also on the ability of the modelling tool to adequately characterise the complex surface and subsurface hydrological processes and parameter distributions, which otherwise results in greater uncertainty and higher degree of errors [19,20].Lowlands are characterised mainly with high GW levels, low hydraulic gradients, and flat topography. This may lead to direct hydraulic interactions between the different subsystems which are not adequately described by pure hydrologic model approaches.…”