A novel approach to estimate direct and indirect water withdrawals from satellite measurements: A case study from the Incomati basin

Eekelen, M.W. van; Bastiaanssen, W.G.M.; Jarmain, C.; Jackson, B. M.; Ferreira, Fernanda Laurinda Valadares; Zaag, Pieter van der; Okello, A. Saraiva; Bosch, Jan; Dye, P. J.; Bastidas-Obando, E.; Dost, R.J.J.; Luxemburg, W. M. J.

doi:10.1016/j.agee.2014.10.023

Cited by 71 publications

(55 citation statements)

References 33 publications

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“…The geology is complex, characterised by sedimentary, volcanic, granitic and dolomitic rocks, as well as Quaternary and recent deposits (Van der Zaag and Vaz, 2003). The soils in the basin are highly variable, ranging from moderately deep clayey loam in the west, to moderately deep sandy loam in the central areas and moderately deep clayey soils in the east.…”

Section: Study Areamentioning

confidence: 99%

“…A recent study by van Eekelen et al (2015) finds that streamflow reduction due to forest plantations may be 2 or even 3 times more than that allowed by the Interim IncoMaputo Agreement.…”

Section: Example Of Decreasing Trends: Noord Kaap X2h010mentioning

confidence: 99%

“…The level of water abstraction in the Incomati River is very high, and the actual water demand is projected to increase in the future, as a result of further economic development and population growth (Nkomo and van der Zaag, 2004;LeMarie et al, 2006;Pollard et al, 2011). The consumptive use of surface water amounts to more than 1880 million cubic metres per annum (10 6 m 3 a −1 ), which represents 51 % of the average amount of surface water generated in the basin (Van der Zaag and Vaz, 2003). The major water consumers (see Tables 1 and 2), accounting for 91 % of all consumptive water use, are the irrigation and forestry sectors, followed by inter-basin water transfers to the Umbeluzi basin and the Olifants catchment in the Limpopo basin (Van der Zaag and Vaz, 2003;DWAF, 2009b;TPTC, 2010).…”

Section: Study Areamentioning

confidence: 99%

“…The consumptive use of surface water amounts to more than 1880 million cubic metres per annum (10 6 m 3 a −1 ), which represents 51 % of the average amount of surface water generated in the basin (Van der Zaag and Vaz, 2003). The major water consumers (see Tables 1 and 2), accounting for 91 % of all consumptive water use, are the irrigation and forestry sectors, followed by inter-basin water transfers to the Umbeluzi basin and the Olifants catchment in the Limpopo basin (Van der Zaag and Vaz, 2003;DWAF, 2009b;TPTC, 2010). Since the 1950s, the area of irrigated agriculture and forestry has increased steadily, particularly in the Komati and Crocodile systems (Table 2).…”

Section: Study Areamentioning

confidence: 99%

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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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Section: Study Areamentioning

confidence: 99%

“…A recent study by van Eekelen et al (2015) finds that streamflow reduction due to forest plantations may be 2 or even 3 times more than that allowed by the Interim IncoMaputo Agreement.…”

Section: Example Of Decreasing Trends: Noord Kaap X2h010mentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

See 2 more Smart Citations

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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“…However, SEB groundwater-ET studies and groundwater-surface water models are still sensitive to accuracy in precipitation data (e.g. Peeters et al, 2013;van Eekelen et al, 2015), which is subject to interpolation errors (Jeffrey et al, 2001;Jones et al, 2009). Furthermore, integrated groundwater-surface water models are highly parameterised, with considerable uncertainty associated with model inputs (Kim et al, 2008).…”

Section: Surface Water and Assessment Tool (Swat) -Modular Three-dimementioning

confidence: 99%

A land surface temperature model-data differencing approach to quantifying subsurface water use by vegetation: Application in the Condamine region, south-eastern Queensland

Gow¹

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Water plays a crucial role in plant community and landscape function; plants use stomata to regulate water loss via transpiration as the 'cost' of carbon assimilation, which in turn regulates surface temperature of leaves. Presently there are a number of aspects of vegetation water-use dynamics that are poorly understood, including the degree of dependence on water sources at different depths in the soil profile; timing, frequency, duration and magnitude of water use; and ecosystem strategies to acquiring water from different sources as water availability varies.The research presented in this thesis aimed to: (1) quantify timing and frequency of the use of subsurface water by woody vegetation, (2) quantify the confidence of these predictions, and (3) identify subsurface water-use strategies and physiological responses employed by woody vegetation with variation in climatic and water-deficit conditions. These aims were achieved through development, application and assessment of a novel land surface temperature (LST) model-data differencing approach applied to a subtropical woodland environment in eastern Australia. The approach detects subsurface water use by vegetation in space and time within 95% confidence intervals, through differences in modelled LST (Ts.mod) and satellite observations of LST (Ts.obs) after accounting for random and systematic error in the model and data.Modelled LST was derived using a two-layer surface energy balance (SEB) model and captures water use from surface water and soil water in the top 30 cm of the soil profile (i.e. shallow soil water). Satellite observations of LST were obtained from Terra-MODIS thermal infrared imagery and captures water use from all available sources. When compared, temperature differences between independently-derived Ts.mod and Ts.obs reveal subsurface water use (i.e. below 30 cm depth) plus systematic and random error. Systematic error or bias, was estimated from temperature differences of grassland vegetation based on an assumption that these vegetation communities do not access subsurface water under certain climatic conditions. Therefore Ts.mod should equal Ts.obs.Random error in Ts.obs was estimated from the literature while sensitivity and uncertainty analyses were used to quantify Ts.mod random error arising from five SEB model resistance terms and their associated input parameters. A Student's t-test was then used to account for systematic and random error in the detection of subsurface water use by vegetation within 95% confidence intervals.The LST model-data differencing approach was applied in a 3200 km 2 region of the subtropical Condamine River Catchment, south-eastern Queensland Australia. The study area contains a mixture of native remnant vegetation, agriculturally-intensive areas, and coal seam gas development. Extensive eucalypt woodlands dominate low-lying hill slopes, while rainfed pastoral grasses and irrigated crops are common throughout the alluvial floodplain and topographic lows adjacent to hill slopes. Timing and frequency ...

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Estimating the sediment trap efficiency of intermittently dry reservoirs: lessons from the Kruger National Park, South Africa

Reinwarth

Riddell

Glotzbach

et al. 2017

Earth Surf Processes Landf

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The assessment of sediment yield from reservoir siltation requires knowledge of the reservoir's sediment trap efficiency (TE). Widely used approaches for the estimation of the long‐term mean TE rely on the ratio of the reservoir's storage capacity (C) to its catchment size (A) or mean annual inflow (I). These approaches have been developed from a limited number of reservoirs (N ≤ 40), most of them located in temperate climate regions. Their general applicability to reservoirs receiving highly variable runoff such as in semi‐arid areas has been questioned. Here, we examine the effect of ephemeral inflow on the TE of 10 small (≤ 280 × 103 m3), intermittently dry reservoirs located in the Kruger National Park. Fieldwork was conducted to determine the storage capacity of the reservoir basins. The frequency and magnitude of spillage events was simulated with the daily time step Pitman rainfall–runoff model. Different runoff scenarios were established to cope with uncertainties arising from the lack of runoff records and imperfect input data. Scenarios for the relationship between water and sediment discharge were created based on sediment rating curves. Taking into account uncertainties in hydrological modelling, uncertainties of mean TE estimates, calculated from all scenarios (N = 9), are moderate, ranging from ±6 to ±11% at the 95% confidence level. By comparison, estimating TE from the storage capacity to catchment area (C/A) ratio induces high uncertainty (ranges of 35 to 65%), but this uncertainty can be confined (15 to 33%) when the latter approach is combined with hydrological modelling. Established methods relying on the storage capacity to mean annual inflow (C/I) ratio most probably lead to an overestimation of the TE for the investigated reservoirs. The approach presented here may be used instead to estimate the TE of small, intermittently dry reservoirs in semi‐arid climate regions. Copyright © 2017 John Wiley & Sons, Ltd.

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A novel approach to estimate direct and indirect water withdrawals from satellite measurements: A case study from the Incomati basin

Cited by 71 publications

References 33 publications

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

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

A land surface temperature model-data differencing approach to quantifying subsurface water use by vegetation: Application in the Condamine region, south-eastern Queensland

Estimating the sediment trap efficiency of intermittently dry reservoirs: lessons from the Kruger National Park, South Africa

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