scholarly journals An Assessment of Land Use and Land Cover Changes and Its Impact on the Surface Water Quality of the Crocodile River Catchment, South Africa

2021 ◽  
Author(s):  
Nde Samuel Che ◽  
Sammy Bett ◽  
Enyioma Chimaijem Okpara ◽  
Peter Oluwadamilare Olagbaju ◽  
Omolola Esther Fayemi ◽  
...  

The degradation of surface water by anthropogenic activities is a global phenomenon. Surface water in the upper Crocodile River has been deteriorating over the past few decades by increased anthropogenic land use and land cover changes as areas of non-point sources of contamination. This study aimed to assess the spatial variation of physicochemical parameters and potentially toxic elements (PTEs) contamination in the Crocodile River influenced by land use and land cover change. 12 surface water samplings were collected every quarter from April 2017 to July 2018 and were analyzed by inductive coupled plasma spectrometry-mass spectrometry (ICP-MS). Landsat and Spot images for the period of 1999–2009 - 2018 were used for land use and land cover change detection for the upper Crocodile River catchment. Supervised approach with maximum likelihood classifier was used for the classification and generation of LULC maps for the selected periods. The results of the surface water concentrations of PTEs in the river are presented in order of abundance from Mn in October 2017 (0.34 mg/L), followed by Cu in July 2017 (0,21 mg/L), Fe in April 2017 (0,07 mg/L), Al in July 2017 (0.07 mg/L), while Zn in April 2017, October 2017 and April 2018 (0.05 mg/L). The concentrations of PTEs from water analysis reveal that Al, (0.04 mg/L), Mn (0.19 mg/L) and Fe (0.14 mg/L) exceeded the stipulated permissible threshold limit of DWAF (< 0.005 mg/L, 0.18 mg/L and 0.1 mg/L) respectively for aquatic environments. The values for Mn (0.19 mg/L) exceeded the permissible threshold limit of the US-EPA of 0.05 compromising the water quality trait expected to be good. Seasonal analysis of the PTEs concentrations in the river was significant (p > 0.05) between the wet season and the dry season. The spatial distribution of physicochemical parameters and PTEs were strongly correlated (p > 0.05) being influenced by different land use type along the river. Analysis of change detection suggests that; grassland, cropland and water bodies exhibited an increase of 26 612, 17 578 and 1 411 ha respectively, with land cover change of 23.42%, 15.05% and 1.18% respectively spanning from 1999 to 2018. Bare land and built-up declined from 1999 to 2018, with a net change of - 42 938 and − 2 663 ha respectively witnessing a land cover change of −36.81% and − 2.29% respectively from 1999 to 2018. In terms of the area under each land use and land cover change category observed within the chosen period, most significant annual change was observed in cropland (2.2%) between 1999 to 2009. Water bodies also increased by 0.1% between 1999 to 2009 and 2009 to 2018 respectively. Built-up and grassland witness an annual change rate in land use and land cover change category only between 2009 to 2018 of 0.1% and 2.7% respectively. This underscores a massive transformation driven by anthropogenic activities given rise to environmental issues in the Crocodile River catchment.

2020 ◽  
Vol 10 (10) ◽  
Author(s):  
Ishtiyaq Ahmad Rather ◽  
Abdul Qayoom Dar

Abstract A dynamic process like land use, if anthropogenically unsustainable, adversely affects the well-being of the land system. Worldwide, water bodies are facing imminent threat due to unsustainable anthropogenic activities. Water quality and ecology are the two characteristics of water bodies, if not preserved, shall have a direct consequence on the well-being of the human systems. Hence it is essential to understand the causes and consequences of the deteriorating water body systems. The condition is particularly grim in Himalayan water body ecosystems, where unplanned and unchecked urbanization has threatened their very existence. In the present study, the dynamics of land use/land cover (LULC) and its impact on the water quality of Dal Lake in Kashmir Himalaya, India has been assessed. We carried out a detailed study wherein changing LULC is analyzed against the deteriorating trophic status of the Dal Lake using time-series of satellite imagery of the lake’s catchment and its water quality data. Results indicated that the water quality of Dal Lake has remarkably deteriorated due to increased nutrient and sediment loads from the catchment, attributed to significant anthropogenic activities in the catchment. Due to unprecedented LULC changes in the catchment, the forest class shows a significantly negative change since the last four decades (1980–2018), corroborating with the ongoing deterioration of physicochemical characteristics of the lake. The analysis shows an increase in all the agents of eutrophication, such as NO3–N, TP, and COD, from 1990 to 2018. The decrease in forest, agriculture, and floating gardens was observed to show a significant negative correlation with the increase in the decadal average values of the COD, NO3–N, and TP for the same corresponding period. Similarly, a positive correlation was found between the increase in built-up, aquatic vegetation, bare surfaces, and these water quality parameters, establishing a strong relationship between the deteriorating condition of the lake and changing LULC. Our findings indicate that changing LULC of the lake’s catchment is one of the critical factors that has significantly contributed toward the deteriorating ecology and water quality of the Dal Lake. This study shall contribute toward the development of the robust conservation strategy in order to save this urban lake from its untimely death.


2020 ◽  
Vol 12 (9) ◽  
pp. 3925 ◽  
Author(s):  
Sonam Wangyel Wang ◽  
Belay Manjur Gebru ◽  
Munkhnasan Lamchin ◽  
Rijan Bhakta Kayastha ◽  
Woo-Kyun Lee

Understanding land use and land cover changes has become a necessity in managing and monitoring natural resources and development especially urban planning. Remote sensing and geographical information systems are proven tools for assessing land use and land cover changes that help planners to advance sustainability. Our study used remote sensing and geographical information system to detect and predict land use and land cover changes in one of the world’s most vulnerable and rapidly growing city of Kathmandu in Nepal. We found that over a period of 20 years (from 1990 to 2010), the Kathmandu district has lost 9.28% of its forests, 9.80% of its agricultural land and 77% of its water bodies. Significant amounts of these losses have been absorbed by the expanding urbanized areas, which has gained 52.47% of land. Predictions of land use and land cover change trends for 2030 show worsening trends with forest, agriculture and water bodies to decrease by an additional 14.43%, 16.67% and 25.83%, respectively. The highest gain in 2030 is predicted for urbanized areas at 18.55%. Rapid urbanization—coupled with lack of proper planning and high rural-urban migration—is the key driver of these changes. These changes are associated with loss of ecosystem services which will negatively impact human wellbeing in the city. We recommend city planners to mainstream ecosystem-based adaptation and mitigation into urban plans supported by strong policy and funds.


2021 ◽  
Vol 14 (1) ◽  
pp. 372
Author(s):  
John Peter Obubu ◽  
Seyoum Mengistou ◽  
Robinson Odong ◽  
Tadesse Fetahi ◽  
Tena Alamirew

Catchments for aquatic ecosystems connect to the water quality of those waterbodies. Land use land cover change activities in the catchments, therefore, play a significant role in determining the water quality of the waterbodies. Research on the relationship between land use and land cover changes and water quality has gained global prominence. Therefore, this study aimed at determining land use, land cover changes in the catchments of L. Kyoga basin, and assessing their connectedness to the lake’s water quality. The GIS software was used to determine eight major land use and land cover changes for 2000, 2010, and 2020. Meanwhile, water quality data was obtained through both secondary and primary sources. Spearman correlation statistical tool in SPSS was used to correlate the land use, land cover changes, and water quality changes over the two-decade study period. The results showed that different land use and land cover activities strongly correlated with particular water quality parameters. For example, agriculture correlated strongly with nutrients like TP, TN, and nitrates and turbidity, TSS, BOD, and temp. The correlation with nitrates was statistically significant at 0.01 confidence limit. The findings of this study agreed with what other authors had found in different parts of the world. The results show that to manage the water quality of L. Kyoga, management of land use, land cover activities in the catchment should be prioritized. Therefore, the results are helpful to decision and policy makers and relevant stakeholders responsible for water management.


2021 ◽  
Vol 9 (1) ◽  
pp. 3045-3053
Author(s):  
Kambo Dero ◽  
Wakshum Shiferaw ◽  
Biruk Zewde

The study was aimed to assess urban induced land use land cover changes in the upper Deme watershed. Three satellite images of 1986, 2002, and 2019 were analyzed by ArcGIS and processed by supervised classification. Land use land cover change in the watershed increased for settlement, bare land, and croplands in the period 1986-2019 by 56.6%, 53%, and 0.25%, respectively. However, the land use land cover change in the watershed decreased for a water body, forest, and grassland by 65%, 57.7%, and 7%, respectively. These enforced to change the work habit and social bases. Out of converted lands, during 1986-2002, 34.9%, 53%, 18%, 40.9%, and 10.6% of bare land, cropland, forest land, grassland, and water bodies, respectively, in the upper Deme watershed were changed into settlement areas. During 2002-2019, 30.7%, 36.8%, 26.9%, 66%, and 33.3% of bare land, cropland, forest land, grassland, and water bodies, respectively, were changed into settlement areas. This shows urbanization results in a different change in economic, social, land use land cover, and watershed management activities in the upper Deme watershed.


2006 ◽  
Vol 174 (1-4) ◽  
pp. 161-179 ◽  
Author(s):  
T. Tsegaye ◽  
D. Sheppard ◽  
K. R. Islam ◽  
W. Tadesse ◽  
A. Atalay ◽  
...  

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