Impact of land-use change on catchment water balance: a case study in the central region of South Africa

AbstractAn assessment study on the impact of land use change through afforestation on catchment water balance was carried out in one of the semi-arid quaternary catchments (C52A) of the Modder River Basin located in the central region of South Africa. The study used ArcGIS and the Soil and Water Assessment Tool (SWAT) to create scenarios of forest cover areas and to simulate the water balance of C52A, respectively. Climatic data from 1993 to 2020 were used to simulate the catchment water balance. The climatic data from 2011 to 2020 were generated using SWAT weather generator while the rest was obtained from South Africa Weather Service at three weather stations located within C52A catchment. In the C52A quaternary catchment it was envisaged to increase forest cover by considering afforestation on pastureland that is found on slopes > 8% and > 3% which created two forest scenarios. The baseline land use [Land use 2000 (LU2000)] which is taken as the base scenario in this study has about 84% of the catchment area covered with pasture. The two forest scenarios created were: forest scenario1 (FRSE1), i.e. conversion of pastureland on slope > 8% to forest, and forest scenario2 (FRSE2), i.e. conversion of pastureland on slope > 3% to forest. The type of forest considered in these scenarios is an evergreen tree, acronym as FRSE by SWAT land use classification. The conversion increased forest cover by 8.3% and 30.5% on FRSE1 and FRSE2, respectively. The result of the water balance of the catchment based on the land use scenarios were compared with the baseline land use scenario (LU2000). The result obtained showed that FRSE1 produced a non-significant change both on the mean monthly surface runoff and water yield compared to LU2000. On the other hand, FRSE2 showed 30% decrease on the mean monthly surface runoff, but increased the mean monthly lateral flow and base flow by 110% and 254%, respectively compared to the LU2000. Thus, in the overall water balance, the mean monthly water yield of the catchment increased by 171% on FRSE2 compared to the LU2000. Although there are considerable number of research reports on the negative effect of forest on catchment water yield, this study showed a significant water yield increase when approximately 30% of the C52A catchment area, which lay on slopes > 3% and covered by grass, was converted to evergreen forest land. The result showed that having a forest cover on a suitable slope range can bring about a positive effect on the total water yield of a catchment. Therefore, this finding is important for catchment management stakeholders and policy-makers when devising land use and water resources management strategies in a catchment.

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Investigating impact of land-use and land cover changes on hydro-ecological balance using GIS: insights from IIT Bombay, India

SN Applied Sciences ◽

10.1007/s42452-021-04328-7 ◽

2021 ◽

Vol 3 (3) ◽

Cited By ~ 1

Author(s):

Aman Srivastava ◽

Pennan Chinnasamy

Keyword(s):

Land Use ◽

Land Cover ◽

Surface Runoff ◽

Forest Cover ◽

Google Earth ◽

Negative Consequences ◽

Ecological Stability ◽

Barren Land ◽

Ecological Balance ◽

Lulc Changes

AbstractThe present study, for the first time, examined land-use land cover (LULC), changes using GIS, between 2000 and 2018 for the IIT Bombay campus, India. Objective was to evaluate hydro-ecological balance inside campus by determining spatio-temporal disparity between hydrological parameters (rainfall-runoff processes), ecological components (forest, vegetation, lake, barren land), and anthropogenic stressors (urbanization and encroachments). High-resolution satellite imageries were generated for the campus using Google Earth Pro, by manual supervised classification method. Rainfall patterns were studied using secondary data sources, and surface runoff was estimated using SCS-CN method. Additionally, reconnaissance surveys, ground-truthing, and qualitative investigations were conducted to validate LULC changes and hydro-ecological stability. LULC of 2018 showed forest, having an area cover of 52%, as the most dominating land use followed by built-up (43%). Results indicated that the area under built-up increased by 40% and playground by 7%. Despite rapid construction activities, forest cover and Powai lake remained unaffected. This anomaly was attributed to the drastically declining barren land area (up to ~ 98%) encompassing additional construction activities. Sustainability of the campus was demonstrated with appropriate measures undertaken to mitigate negative consequences of unwarranted floods owing to the rise of 6% in the forest cover and a decline of 21% in water hyacinth cover over Powai lake. Due to this, surface runoff (~ 61% of the rainfall) was observed approximately consistent and being managed appropriately despite major alterations in the LULC. Study concluded that systematic campus design with effective implementation of green initiatives can maintain a hydro-ecological balance without distressing the environmental services.

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Modelling monthly runoff generation processes following land use changes: groundwater–surface runoff interactions

Hydrology and Earth System Sciences ◽

10.5194/hess-8-903-2004 ◽

2004 ◽

Vol 8 (5) ◽

pp. 903-922 ◽

Cited By ~ 13

Author(s):

M. Bari ◽

K. R. J. Smettem

Keyword(s):

Land Use ◽

Water Balance ◽

Surface Runoff ◽

Land Use Changes ◽

Annual Rainfall ◽

Rainfall Runoff ◽

Runoff Generation ◽

Mean Annual Rainfall ◽

Monthly Runoff ◽

Stream Bed

Abstract. A conceptual water balance model is presented to represent changes in monthly water balance following land use changes. Monthly rainfall–runoff, groundwater and soil moisture data from four experimental catchments in Western Australia have been analysed. Two of these catchments, "Ernies" (control, fully forested) and "Lemon" (54% cleared) are in a zone of mean annual rainfall of 725 mm, while "Salmon" (control, fully forested) and "Wights" (100% cleared) are in a zone with mean annual rainfall of 1125 mm. At the Salmon forested control catchment, streamflow comprises surface runoff, base flow and interflow components. In the Wights catchment, cleared of native forest for pasture development, all three components increased, groundwater levels rose significantly and stream zone saturated area increased from 1% to 15% of the catchment area. It took seven years after clearing for the rainfall–runoff generation process to stabilise in 1984. At the Ernies forested control catchment, the permanent groundwater system is 20 m below the stream bed and so does not contribute to streamflow. Following partial clearing of forest in the Lemon catchment, groundwater rose steadily and reached the stream bed by 1987. The streamflow increased in two phases: (i) immediately after clearing due to reduced evapotranspiration, and (ii) through an increase in the groundwater-induced stream zone saturated area after 1987. After analysing all the data available, a conceptual monthly model was created, comprising four inter-connecting stores: (i) an upper zone unsaturated store, (ii) a transient stream zone store, (ii) a lower zone unsaturated store and (iv) a saturated groundwater store. Data such as rooting depth, Leaf Area Index, soil porosity, profile thickness, depth to groundwater, stream length and surface slope were incorporated into the model as a priori defined attributes. The catchment average values for different stores were determined through matching observed and predicted monthly hydrographs. The observed and predicted monthly runoff for all catchments matched well with coefficients of determination (R2) ranging from 0.68 to 0.87. Predictions were relatively poor for: (i) the Ernies catchment (lowest rainfall, forested), and (ii) months with very high flows. Overall, the predicted mean annual streamflow was within ±8% of the observed values. Keywords: monthly streamflow, land use change, conceptual model, data-based approach, groundwater

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The importance of glacier and forest change in hydrological climate-impact studies

Hydrology and Earth System Sciences ◽

10.5194/hess-17-619-2013 ◽

2013 ◽

Vol 17 (2) ◽

pp. 619-635 ◽

Cited By ~ 15

Author(s):

N. Köplin ◽

B. Schädler ◽

D. Viviroli ◽

R. Weingartner

Keyword(s):

Land Cover ◽

Water Balance ◽

Catchment Area ◽

Forest Cover ◽

Control Period ◽

Climate Impact ◽

Glacier Retreat ◽

Climate Scenarios ◽

Forest Change ◽

Impact Studies

Abstract. Changes in land cover alter the water balance components of a catchment, due to strong interactions between soils, vegetation and the atmosphere. Therefore, hydrological climate impact studies should also integrate scenarios of associated land cover change. To reflect two severe climate-induced changes in land cover, we applied scenarios of glacier retreat and forest cover increase that were derived from the temperature signals of the climate scenarios used in this study. The climate scenarios were derived from ten regional climate models from the ENSEMBLES project. Their respective temperature and precipitation changes between the scenario period (2074–2095) and the control period (1984–2005) were used to run a hydrological model. The relative importance of each of the three types of scenarios (climate, glacier, forest) was assessed through an analysis of variance (ANOVA). Altogether, 15 mountainous catchments in Switzerland were analysed, exhibiting different degrees of glaciation during the control period (0–51%) and different degrees of forest cover increase under scenarios of change (12–55% of the catchment area). The results show that even an extreme change in forest cover is negligible with respect to changes in runoff, but it is crucial as soon as changes in evaporation or soil moisture are concerned. For the latter two variables, the relative impact of forest change is proportional to the magnitude of its change. For changes that concern 35% of the catchment area or more, the effect of forest change on summer evapotranspiration is equally or even more important than the climate signal. For catchments with a glaciation of 10% or more in the control period, the glacier retreat significantly determines summer and annual runoff. The most important source of uncertainty in this study, though, is the climate scenario and it is highly recommended to apply an ensemble of climate scenarios in the impact studies. The results presented here are valid for the climatic region they were tested for, i.e., a humid, mid-latitude mountainous environment. They might be different for regions where the evaporation is a major component of the water balance, for example. Nevertheless, a hydrological climate-impact study that assesses the additional impacts of forest and glacier change is new so far and provides insight into the question whether or not it is necessary to account for land cover changes as part of climate change impacts on hydrological systems.

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Impact of Arable Land to Grassland Conversion on the Vegetation-period Water Balance of a Small Agricultural Catchment (Němčický Stream)

Soil and Water Research ◽

10.17221/7/2010-swr ◽

2010 ◽

Vol 5 (No. 4) ◽

pp. 128-138 ◽

Cited By ~ 2

Author(s):

P. Kovář ◽

D. Vaššová

Keyword(s):

Land Use ◽

Land Use Change ◽

Water Balance ◽

Surface Runoff ◽

Arable Land ◽

Vegetation Period ◽

Water Balance Components ◽

Total Runoff ◽

Grassland Conversion ◽

Pronounced Reduction

This paper presents results of decadal (10-day) water balance simulations for the vegetation periods (April to October) of 2001 (normal year), 2002 (wet year) and 2003 (dry year) in the Němčický Stream experimental catchment (3.52 km<sup>2</sup>). The catchment is a typical agricultural area with a large extent of arable land. This paper shows that the model used (WBCM) is capable of reliably simulating decadal water balance components for the actual land use. The same model is then used to estimate water balance changes brought about when 10% of arable land has been transformed into permanent grassland. It is shown that this land use change results in a pronounced reduction of surface runoff and an increase in subsurface storage over the vegetation periods of all three years. The vegetation period groundwater runoff was only enhanced in the wet year, while the total runoff was reduced in all three years. 

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Hydrological Responses to Climate and Land Use Changes in a Watershed of the Loess Plateau, China

Sustainability ◽

10.3390/su11051443 ◽

2019 ◽

Vol 11 (5) ◽

pp. 1443 ◽

Cited By ~ 10

Author(s):

Rui Yan ◽

Yanpeng Cai ◽

Chunhui Li ◽

Xuan Wang ◽

Qiang Liu

Keyword(s):

Climate Change ◽

Land Use ◽

Water Balance ◽

Loess Plateau ◽

Climate Changes ◽

Land Use Changes ◽

Water Yield ◽

The Loess Plateau ◽

Runoff Water ◽

Lulc Change

This study researched the individual and combined impacts of future LULC and climate changes on water balance in the upper reaches of the Beiluo River basin on the Loess Plateau of China, using the scenarios of RCP4.5 and 8.5 of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC). The climate data indicated that both precipitation and temperature increased at seasonal and annual scales from 2020 to 2050 under RCP4.5 and 8.5 scenarios. The future land use changes were predicted through the CA-Markov model. The land use predictions of 2025, 2035, and 2045 indicated rising forest areas with decreased agricultural land and grassland. In this study, three scenarios including only LULC change, only climate change, and combined climate and LULC change were established. The SWAT model was calibrated, validated, and used to simulate the water balance under the three scenarios. The results showed that increased rainfall and temperature may lead to increased runoff, water yield, and ET in spring, summer, and autumn and to decreased runoff, water yield, and ET in winter from 2020 to 2050. However, LULC change, compared with climate change, may have a smaller impact on the water balance. On an annual scale, runoff and water yield may gradually decrease, but ET may increase. The combined effects of both LULC and climate changes on water balance in the future were similar to the variation trend of climate changes alone at both annual and seasonal scales. The results obtained in this study provide further insight into the availability of future streamflow and can aid in water resource management planning in the study area.

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Watershed Hydrological Response to Combined Land Use/Land Cover and Climate Change in Highland Ethiopia: Finchaa Catchment

Water ◽

10.3390/w12061801 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1801 ◽

Cited By ~ 1

Author(s):

Wakjira Takala Dibaba ◽

Tamene Adugna Demissie ◽

Konrad Miegel

Keyword(s):

Climate Change ◽

Land Use ◽

Water Resources ◽

Land Cover ◽

Surface Runoff ◽

Regional Climate ◽

Water Yield ◽

Land Use Land Cover ◽

Ensemble Mean ◽

The Future

Land use/land cover (LULC) and climate change affect the availability of water resources by altering the magnitude of surface runoff, aquifer recharge, and river flows. The evaluation helps to identify the level of water resources exposure to the changes that could help to plan for potential adaptive capacity. In this research, Cellular Automata (CA)-Markov in IDRISI software was used to predict the future LULC scenarios and the ensemble mean of four regional climate models (RCMs) in the coordinated regional climate downscaling experiment (CORDEX)-Africa was used for the future climate scenarios. Distribution mapping was used to bias correct the RCMs outputs, with respect to the observed precipitation and temperature. Then, the Soil and Water Assessment Tool (SWAT) model was used to evaluate the watershed hydrological responses of the catchment under separate, and combined, LULC and climate change. The result shows the ensemble mean of the four RCMs reported precipitation decline and increase in future temperature under both representative concentration pathways (RCP4.5 and RCP8.5). The increases in both maximum and minimum temperatures are higher for higher emission scenarios showing that RCP8.5 projection is warmer than RCP4.5. The changes in LULC brings an increase in surface runoff and water yield and a decline in groundwater, while the projected climate change shows a decrease in surface runoff, groundwater and water yield. The combined study of LULC and climate change shows that the effect of the combined scenario is similar to that of climate change only scenario. The overall decline of annual flow is due to the decline in the seasonal flows under combined scenarios. This could bring the reduced availability of water for crop production, which will be a chronic issue of subsistence agriculture. The possibility of surface water and groundwater reduction could also affect the availability of water resources in the catchment and further aggravate water stress in the downstream. The highly rising demands of water, owing to socio-economic progress, population growth and high demand for irrigation water downstream, in addition to the variability temperature and evaporation demands, amplify prolonged water scarcity. Consequently, strong land-use planning and climate-resilient water management policies will be indispensable to manage the risks.

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The importance of glacier and forest change in hydrological climate-impact studies

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-9-5983-2012 ◽

2012 ◽

Vol 9 (5) ◽

pp. 5983-6021 ◽

Cited By ~ 3

Author(s):

N. Köplin ◽

B. Schädler ◽

D. Viviroli ◽

R. Weingartner

Keyword(s):

Land Cover ◽

Water Balance ◽

Catchment Area ◽

Forest Cover ◽

Control Period ◽

Climate Impact ◽

Glacier Retreat ◽

Climate Scenarios ◽

Forest Change ◽

Impact Studies

Abstract. Changes in land cover alter the water balance components of a catchment, due to strong interactions between soils, vegetation and the atmosphere. Therefore, hydrological climate impact studies should also integrate scenarios of associated land cover change. To reflect two severe climate-induced changes in land cover, we applied scenarios of glacier retreat and forest cover increase that were derived from the temperature signals of the climate scenarios used in this study. The climate scenarios consist of ten regional climate models from the ENSEMBLES project; their respective temperature and precipitation deltas are used to run a hydrological model. The relative importance of each of the three types of scenarios (climate, glacier, forest) is assessed through an analysis of variance (ANOVA). Altogether, 15 mountainous catchments in Switzerland are analysed, exhibiting different degrees of glaciation during the control period (0–51%) and different degrees of forest cover increase under scenarios of change (12–55% of the catchment area). The results show that even an extreme change in forest cover is negligible with respect to changes in runoff, but it is crucial as soon as evaporation or soil moisture is concerned. For the latter two variables, the relative impact of forest change is proportional to the magnitude of its change. For changes that concern 35% of the catchment area or more, the effect of forest change on summer evapotranspiration is equally or even more important than the climate signal. For catchment with a glaciation of 10% or more in the control period, the glacier retreat significantly determines summer and annual runoff. The most important source of uncertainty in hydrological climate impact studies is the climate scenario, though, and it is highly recommended to apply an ensemble of climate scenarios in impact studies. The results presented here are valid for the climatic region they were tested for, i.e. a humid, mid-latitude mountainous environment. They might be different for regions where the evaporation is a major component of the water balance, for example. Nevertheless, a hydrological climate-impact study that assesses the additional impacts of forest and glacier change is new so far and provides insight into the question whether or not it is necessary to account for land cover changes as part of climate change impacts on hydrological systems.

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Assessing the Impact of land-use types on the groundwater quality: a case study of Mid River Njoro Catchment, Kenya

Acque Sotterranee-Italian Journal of Groundwater ◽

10.7343/as-2020-350 ◽

2020 ◽

Vol 9 (4) ◽

Author(s):

Halake Guyo Rendilicha ◽

Patrick Home ◽

James M. Raude ◽

Charles M. M’Erimba ◽

Stellamaris Muthoka

Keyword(s):

Land Use ◽

Groundwater Quality ◽

Forest Cover ◽

Agricultural Land ◽

Settlement Area ◽

Mixed Area ◽

Land Use Types ◽

The Mean ◽

The Impact

The study assessed the impact of land-use types on the groundwater quality of the mid River Njoro catchment, Kenya. Groundwater samples were collected from eight boreholes between the period of October 2017 to February 2018 and analyzed for pH, temperature, electrical conductivity, dissolved oxygen, nitrate, ammonium, and total phosphorus. These parameters were used to calculate the Groundwater Quality Index (GQI) value of the study area. The concentration maps (“primary maps I”) were constructed using Kriging interpolation of ArcGIS software from the seven groundwater quality parameters. The “primary maps I” were standardized with the KEBS and WHO standards to the “primary maps II” for ease of integration into a GIS environment. The “primary maps II” were then rated and weighted using a polynomial function to generate “rank maps” before calculating the GQI using spatial analyst tools of ArcGIS software. The land use map was prepared from a high-resolution Google earth satellite imagery of 2015. The mean GQI values for the different land use polygons were calculated and compared using GIS techniques. The GQI ranged from 68.38 to 70.92, indicating a high groundwater quality of mid River Njoro catchment. The major land-use types identified include settlement area, forest cover, agricultural land and mixed area. The agricultural land dominated the study area, followed by settlement area, forest cover and finally mixed area. The mean GQI value in each land use type varied minimally and this could be because of the diffuse nature of the land use types of the study area. Settlement area had low GQI, followed by agricultural land, mixed area and the forest cover had the highest mean GQI value, which corresponds to good quality of groundwater. Even though the variation is insignificant in this particular study, it somehow indicates the adverse effects of different land use on the quality of groundwater.

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Effects of catchment area forestation on the temperature of river waters

Forest Research Papers ◽

10.1515/frp-2017-0028 ◽

2017 ◽

Vol 78 (3) ◽

pp. 251-256 ◽

Cited By ~ 5

Author(s):

Mariusz Ptak

Keyword(s):

Water Temperature ◽

Catchment Area ◽

Forest Cover ◽

Thermal Conditions ◽

Buffer Zone ◽

River Waters ◽

Daily Water ◽

The Mean ◽

Annual Water ◽

The Impact

Abstract The objective of this paper was to analyse the effects of catchment area forestation on the temperature of river waters. Two rivers, Czerna Wielka and Szprotawa, were covered in this research project and both are located in south-west Poland, running through the largest compact forest complex in the country, Bory Dolnośląskie. Both of the rivers are located within the same climatic region, and are similar in terms of their hydrology. Land use in the catchment area however is very diverse with 71.6% forest cover in the case of the Czerna Wielka River and direct contact of the forest with the river occurs over 68.3% of its length. For the Szprotawa River, the indices amount to only 39.3% and 21.6%, respectively. Data on the daily water temperatures for both of the rivers were obtained from the Hydrological Yearbooks of Surface Waters for the period 1969–1983. The mean annual water temperature in the analysed period in the case of the Czerna Wielka River amounted to 8.0°C, and in the case of the Szprotawa River it equalled 9.2°C. During the cooler half of the year (November-April), the mean water temperature for the entire examined period amounted to 3.8°C for Czerna Wielka, and 3.6°C for Szprotawa. Higher variability was recorded for the warmer seasons (May-October), where mean temperatures amounted to 12.1°C and 14.7°C, respectively. The obtained results concur with other similar research conducted around the world, and in the context of climate change are of practical value. The important role of forests in the moderation of thermal conditions is evidently unquestionable. Therefore, minimising the impact of unfavourable climatic changes on river ecosystems and their surroundings requires striving for appropriate forest management in the near-bank (buffer) zone along banks of both larger rivers and their tributaries

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Analysis of the effect of land use changes on hydrology characteristics. Case study: the catchment area of Koto Panjang Hydroelectric Power

MATEC Web of Conferences ◽

10.1051/matecconf/201927604014 ◽

2019 ◽

Vol 276 ◽

pp. 04014

Author(s):

Nurdin ◽

Syaiful Bahri ◽

Zulkarnain ◽

Sukendi

Keyword(s):

Land Use ◽

Catchment Area ◽

Hydrological Model ◽

Land Use Changes ◽

Water Yield ◽

Runoff Coefficient ◽

Hydroelectric Power ◽

Hydrological Characteristics ◽

Effects Of Land Use

This study aims to analyze the hydrological characteristics as a result of changes in land use with the help of the SWAT hydrological model and can provide recommendations on the best land use in the Koto Panjang Electric Power catchment area. Based on the results of the analysis using the SWAT hydrological model, it was seen that there were effects of land use changes in 2011 and 2014 on hydrological characteristics; yield of water (WATER YLD) of 2,413.38 mm, and 1.008, 65 mm, runoff coefficient (C) of 0.19 and 0.063 respectively, and river regime coefficient (KRS) of 11.449 and 12.212, respectively. The best land use to be developed in agricultural cultivation areas as a recommendation to maintain water stability in the Koto Panjang hydropower catchment area is a simple and complex agroforestry pattern in scenario III, which is run together with hydrological characteristics in the form; water yield (WATER YLD) of 1,038.41, surface runoff coefficient (C) of 0.023, and river regime coefficient (KRS) of 11.13. The hydrological characteristics in scenario III are far better than 2014 land use characteristics (existing).

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