Urban Heat Islands (UHIs) are urban areas that are relatively warmer than nearby rural areas due to the presence of infrastructures, such as buildings, roads, and associated development. This study explored the UHIs in Nepal's three largest metropolitan cities, i.e., Pokhara, Bharatpur, and Nepalgunj. Using freely available data, we explored LST dynamics between 2000 and 2019 and how changes in NDVI affect LST and their relationship with UHI. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) 8-day product (MOD11A2) to evaluate LST and the MODIS-derived NDVI 16-day product (MOD13Q1) to quantify land surface characteristics. Using a simple linear regression technique, we explored the relationship between LST and NDVI. The results indicated that LSTs for the urban areas are consistently greater than LSTs for the nearby rural areas, and an inverse relation between LST and NDVI was obtained. The results from Pokhara and Bharatpur showed that increasing LST resulting from declining NDVI is responsible for UHIs. However, the results from Nepalgunj suggested that factors other than NDVI are responsible for variation in LST. These results indicate a need for systematic mapping, planning, and managing open and green areas in large cities. This research also highlights the scope of applying UHI conceptual models to rapidly developing urban areas in different locations of Nepal for better planning and management of open spaces.
Urban agriculture is regaining popularity as a method of food cultivation to meet the food needs of communities that reside in densely populated areas. Although this method of farming has many benefits, little research has evaluated the potential impacts of practice on the environment, such as water quality resulting from nutrient runoff. To address this gap, this study analyzed runoff water collected from raised beds and small plastic pool container plots with four different types of nutrient management treatments (conventional fertilizer, organic fertilizer, low-compost + organic fertilizer, and high compost). Water samples were collected from each of the raised bed and container plots once per month, weather permitting, and analyzed for pH, conductivity, color, turbidity, nitrate-nitrogen, ammonia-nitrogen, total phosphorus, and potassium. Although there were some significant differences between the raised beds and container plots, they did not translate to meaningful differences in water quality for most variables measured, except for nitrate-nitrogen. The conventional fertilizer treatment demonstrated greater or more variable nutrient leaching than the other nutrient management treatments. This result suggests an opportunity for improved nutrient management by urban farmers to reduce nutrient leaching. Sampling time was found to have a significant impact on runoff water quality, which could be attributed to varying precipitation rates between samplings and timing of sampling in relation to compost and fertilizer applications, and crop production cycles.
Land cover change is prevalent in the eastern Kentucky Appalachian region, mainly due to increased surface mining activities. This study explored the potential change in land cover and its relationship with stream discharge and sediment yield in a watershed of the Cumberland River near Harlan, Kentucky, between 2001 and 2016, using the Soil and Water Assessment Tool (SWAT). Two land cover scenarios for the years 2001 and 2016 were used separately to simulate the surface runoff and sediment yield at the outlet of the Cumberland River near Harlan. Land cover datasets from the National Land Cover Database (NLCD) were used to reclassify the land cover type into the following classes: water, developed, forest, barren, shrubland, and pasture/grassland. Evaluation of the relationship between the land cover change on discharge and sediment was performed by comparing the average annual basin values of streamflow and sediment from each of the land cover scenarios. The SWAT model output was evaluated based on several statistical parameters, including the Nash–Sutcliffe efficiency coefficient (NSE), RMSE-observations standard deviation ratio (RSR), percent bias (PBIAS), and the coefficient of determination (R²). Moreover, P-factor and R-factor indices were used to measure prediction uncertainty. The model showed an acceptable range of agreement for both calibration and validation between observed and simulated values. The temporal land cover change showed a decrease in forest area by 2.42% and an increase in developed, barren, shrubland, and grassland by 0.11%, 0.34%, 0.53%, and 1.44%, respectively. The discharge increased from 92.34 mm/year to 104.7 mm/year, and sediment increased from 0.83 t/ha to 1.63 t/ha from 2001 to 2016, respectively. Based on results from the model, this study concluded that the conversion of forest land into other land types could contribute to increased surface runoff and sediment transport detached from the soil along with runoff water. The research provides a robust approach to evaluating the effect of temporal land cover change on Appalachian streams and rivers. Such information can be useful for designing land management practices to conserve water and control soil erosion in the Appalachian region of eastern Kentucky.
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