Simulating wetland impacts on stream flow in southern Africa using a monthly hydrological model

Hughes, Denis A.; Tshimanga, Raphael M.; Tirivarombo, Sithabile; Tanner, Jane

doi:10.1002/hyp.9725

Cited by 34 publications

(19 citation statements)

References 29 publications

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“…Water is an important resource for the economic and social well-being of humankind [1,2]. In semi-arid regions such as the LRB, adequate water supply to support agriculture, industry, and domestic use is an enduring problem.…”

Section: Introductionmentioning

confidence: 99%

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Mosase

Ahiablame

2018

Water

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Understanding temporal and spatial characteristics of regional climate is essential for decision making in water resource management. Established statistical and GIS techniques were used to evaluate annual and seasonal variations of rainfall and temperature in time and space from 1979 to 2013 in the Limpopo River Basin (LRB). Annual means of rainfall in the LRB varied between 160 and 1109 mm, generally from west to east of the basin during the study period. Annual minimum and maximum temperature ranged from 8 • C in the south to 20 • C in the east of the basin, and 23 • C in the south of the basin to 32 • C in the east. The respective coefficients of variation (CVs) of these variables showed an inverse pattern to the annual values, with rainfall having high CV values (28% to 70% from east to west of the basin) compared to temperature CV values. Seasonal variations followed similar patterns as annual variations for the individual variables examined. Trend analysis showed upward trends for both annual and seasonal rainfall in most parts of the basin, except for the winter season which showed a decreasing trend. Analysis of minimum temperature on an annual basis and for the winter season and spring season shows upward trends during the study period over the whole basin while minimum temperature for summer and autumn showed decreasing trends. Maximum temperature, by contrast, showed decreasing trends on an annual, summer, autumn, and spring basis but an increasing trend for winter during the study period in most parts of the basin.

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Section: Introductionmentioning

confidence: 99%

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Mosase

Ahiablame

2018

Water

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“…In 1973, Pitman (1973 developed a MWBM with twelve parameters to describe the hydrological processes in South Africa. Since then, new model functions such as reservoir submodel, wetland sub-model and groundwater recharge sub-model have been successively added to Pitman model (Hughes, 2004;Hughes et al, 2013). This model including more than 20 parameters is likely the most complex model among the existing MWBMs (Hughes, 2013).…”

Section: Introductionmentioning

confidence: 99%

Comparison of performance of twelve monthly water balance models in different climatic catchments of China

Bai

Liu

Liang

et al. 2015

Journal of Hydrology

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Keywords: Monthly water balance model Model comparison Model selection a b s t r a c tMulti-model comparison can provide useful information for model selection and improvement. In this study, twelve monthly water balance models with different structures and various degree of complexity are compared in 153 catchments with different climatic conditions in China. Generally, the GR5M model has the best performance, followed by the GR2M and WBM model. We investigate the relations between model performance and catchment characteristics and find that the climatic characteristic of a catchment is the most important factor impacting model performance. The models have better performance in wet catchments than in dry catchments. Large differences of model performance exist in dry catchments and model users should pay attention to model selection in dry catchments. In addition, we analyze the model performances among different models and conclude that increasing the model complexity does not guarantee a better model performance. Simple models can achieve comparable or even better performance than complex models. For the monthly simulation of hydrological processes, a two-parameter model is sufficient to achieve a good result. Moreover, by comparing the impacts of evapotranspiration simulation and runoff generation simulation on model performance, we find that evapotranspiration simulation has limited influence on the model performance. We suggest model builders focus on runoff generation process rather than evapotranspiration process to improve the performance of a monthly hydrological model.

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“…In order to manage water in a sustainable manner, it is important to have a sound understanding of the processes that control its existence, the variability in time and space, and our ability to quantify that variability (Jewitt et al, 2004;Hu et al, 2011;Montanari et al, 2013;Hughes et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Drivers of spatial and temporal variability of streamflow in the Incomati River basin

Okello

Masih

Uhlenbrook

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. The Incomati is a semi-arid trans-boundary river basin in southern Africa, with a high variability of streamflow and competing water demands from irrigated agriculture, energy, forestry and industries. These sectors compete with environmental flows and basic human water needs, resulting in a "stressed" water resource system. The impacts of these demands, relative to the natural flow regime, appear significant. However, despite being a relatively well-gauged basin in South Africa, the natural flow regime and its spatial and temporal variability are poorly understood and remain poorly described, resulting in a limited knowledge base for water resource planning and management decisions. Thus, there is an opportunity to improve water management, if it can be underpinned by a better scientific understanding of the drivers of streamflow availability and variability in the catchment.In this study, long-term rainfall and streamflow records were analysed. Statistical analysis, using annual anomalies, was conducted on 20 rainfall stations, for the period 1950-2011. The Spearman test was used to identify trends in the records on annual and monthly timescales. The variability of rainfall across the basin was confirmed to be high, both intraand inter-annually. The statistical analysis of rainfall data revealed no significant trend of increase or decrease. Observed flow data from 33 gauges were screened and analysed, using the Indicators of Hydrologic Alteration (IHA) approach. Temporal variability was high, with the coefficient of variation of annual flows in the range of 1 to 3.6. Significant declining trends in October flows, and low flow indicators, were also identified at most gauging stations of the Komati and Crocodile sub-catchments; however, no trends were evident in the other parameters, including high flows. The trends were mapped using GIS and were compared with historical and current land use. These results suggest that land use and flow regulation are larger drivers of temporal changes in streamflow than climatic forces. Indeed, over the past 40 years, the areas under commercial forestry and irrigated agriculture have increased over 4 times.

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Simulating wetland impacts on stream flow in southern Africa using a monthly hydrological model

Cited by 34 publications

References 29 publications

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Comparison of performance of twelve monthly water balance models in different climatic catchments of China

Drivers of spatial and temporal variability of streamflow in the Incomati River basin

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