Effects Of Land Use Cover Change Research Articles

Isolating the Impacts of Land Use/Cover Change and Climate Change on the GPP in the Heihe River Basin of China

AbstractTerrestrial gross primary production (GPP) is a key indicator of the ecosystem response to climate change and land use/cover change (LUCC) in arid areas. The available global GPP data sets cannot meet the demands for local applications in arid areas due to sparse vegetation and extreme climate conditions. Here, we developed a novel GPP estimation model for the Heihe River Basin (HRB), the second largest inland river basin in northern China, and disentangled the impacts of climate change and LUCC on GPP. First, we calibrated the vegetation photosynthesis model (VPM) using CO2 flux observations from multiple stations in the HRB and developed a modified local GPP model (HRB‐VPM). Then, we decoupled the joint effects of LUCC and climate change on GPP based on the log and differential transformation method. The results showed that HRB‐VPM outperformed Moderate Resolution Imaging Spectroradiometer and VPM GPP models in arid ecosystems. The root mean square error of HRB‐VPM was 4.9 and 1.5 gCm−2 day−1 lower than those of the Moderate Resolution Imaging Spectroradiometer and VPM models, respectively. We concluded that the underlying driving forces of the GPP changes were distinct across the HRB. In the upper reach, climate change accounted for 65.8% of GPP changes, while in the middle and lower reaches, LUCC contributed to 75.1% of GPP changes. Our research provides an effective way to monitor arid ecosystem degradation and is useful for mitigating the negative impacts of human activities and future climate change.

Effects of Landscape Changes on Soil Erosion in the Built Environment: Application of Geospatial-Based RUSLE Technique

The world’s ecosystem is severely affected by the increase in the rate of soil erosion and sediment transport in the built environment and agricultural lands. Land use land cover changes (LULCC) are considered as the most significant cause of sediment transport. This study aims to estimate the effect of LULCC on soil erosion potential in the past 20 years (2000–2020) by using Revised Universal Soil Loss Equation (RUSLE) model based on Geographic Information System (GIS). Different factors were analyzed to study the effect of each factor including R factor, K factor, LS factor, and land cover factor on the erosion process. Maps generated in the study show the changes in the severity of soil loss in the Chitral district of Pakistan. It was found out that 4% of the area was under very high erosion risk in the year 2000 which increased to 8% in the year 2020. An increase in agricultural land (4%) was observed in the last 20 years which shows that human activities largely affected the study area. The outcomes of this study will help the stakeholders and regulatory decision makers to control deforestation and take other necessary actions to minimize the rate of soil erosion. Such an efficient planning will also be helpful to reduce the sedimentation in the reservoir of hydraulic dam(s) constructed on Chitral river, which drains through this watershed.

Assessing the impact of land use land cover changes on land surface temperature over Pune city, India

The intensification of land surface temperature (LST) is a consequence of changes in land use land cover (LULC). Variation of LST and LULC can be extracted from satellite images in different spatial and temporal resolutions. Thus, in the present study, we have used remote sensing and GIS techniques to quantify the land surface temperature variation over different land use land cover classes from 1990 to 2019 using Landsat data in Pune city. Furthermore, the effect of LULC changes on seasonal land surface temperature modification over the urbanized area is also assessed in this study. The result suggests an overall increase of built-up area from 116.6 km2 in 1990 to 166.9 km2 in 2019, witnessing a 43.1% rise during the study period, while the other LULC classes show a decreasing trend, most significantly by agriculture (40.8%) followed by scrubland (37.1%), fallow land (22%), water body (11.1%) and vegetation (2.8%). The 2009–2019 decade was found to be most significant in terms of change in LULC aerial extent over the city as compared to the other two decades (1990–1999 and 1999–2009). The overall mean land surface temperature over the city shows an increasing trend during the summer season (5.8%) and decreasing in the winter season (12.4%) from 1990 to 2019. The change in mean LST over different LULC classes shows a significant increasing and positive trend during the summer season as compared to the negative and decreasing trend of the winter season. The mean LST over agriculture, shrub land, water body, and fallow land shows an increasing trend as compared to the built-up area during both summer and winter season from 1990 to 2019. Furthermore, the study also confirms a higher LST over the surrounding rural area by 1.4 °C, as compared to the city urban area, which suggests the occurrence of the urban cool island over the city. The results of the present study will be very helpful for an urban planner and policymakers to evaluate the current urbanization status and improve their decisions to make cities better and sustaining in the future.

Land use change affects water erosion in the Nepal Himalayas.

Soil erosion is a global environmental threat, and Land Use Land Cover Changes (LUCC) have significant impacts on it. Nepal, being a mountainous country, has significant soil erosion issues. To examine the effects of LUCC on water erosion, we studied the LUCC in Sarada, Rapti and Thuli Bheri river basins of Nepal during the 1995–2015 period using the Remote Sensing. We calculated the average annual soil loss using the Revised Universal Soil Loss Equation and Geographical Information System. Our results suggest that an increase in the agricultural lands at the expense of bare lands and forests escalated the soil erosion through the years; rates being 5.35, 5.47 and 6.03 t/ha/year in 1995, 2007 and 2015, respectively. Of the different land uses, agricultural land experienced the most erosion, whereas the forests experienced the least erosion. Agricultural lands, particularly those on the steeper slopes, were severely degraded and needed urgent soil and water conservation measures. Our study confirms that the long term LUCC has considerable impacts on soil loss, and these results can be implemented in similar river basins in other parts of the country.

Combined effects of urbanization and climate change on watershed evapotranspiration at multiple spatial scales

How urbanization-associated land use/land cover change (LULCC) affects the ecohydrological cycle through altering evapotranspiration (ET) processes is not clear for rice paddy dominated watersheds. The purpose of this study was to understand long-term (2000–2013) spatial and temporal variations of ET over the Qinhuai River Basin in a humid region, southern China. We revised the Soil and Water Assessment Tool (SWAT) by incorporating new algorithms describing hydrological processes of rice paddies. Using the improved SWAT model driven by remote sensing-derived LULCC and local climatic data, we separated the effects of LULCC on ET from climate at the watershed scale. We showed that the modified SWAT model significantly improved monthly streamflow estimates. The Nash-Sutcliffe model efficiency (NSE) was 0.86 and coefficient of determination (R2) was 0.88 for the calibration period (1990–1994) while the NSE was 0.65 and R2 was 0.71 for the validation period (1995–1999). We also found good agreements between modelled daily ET and lysimeter-based measurements for an experimental rice paddy field (R2 = 0.75, p less than 0.01). For areas with little land cover change, ET rates increased over time due to the increase in potential ET (PET) during 2000–2013. However, the contribution from rice paddy to the watershed-level ET decreased over time coincident with a period of rapid urbanization and loss of rice paddy field. Dynamic attribution analysis indicated that the negative contribution of LULCC to change in ET increased from 53% in 2000 to 61% in 2013 while the positive contribution of climate variability decreased from 47% in 2000 to 39% in 2013. We concluded that factors affecting ET varied with spatial scale. Conversion of rice paddy field to urban use directly resulted in significant ET reduction at the watershed scale despite the rise in the air temperature and potential ET in the study region. The improved SWAT model provides a better integrated method for understanding ET processes and assessing the impacts of environmental change on ecosystem services in a rapidly urbanizing region.

Individual and combined impacts of future land-use and climate conditions on extreme hydrological events in a representative basin of the Yangtze River Delta, China

Land use/cover changes (LUCC) as well as climate change have the potential to significantly alter the characteristics of extreme hydrological events under changing environments. This study evaluates the individual and combined impacts that LUCC and climate change have on extreme hydrological events using Soil and Water Assessment Tool (SWAT) applied in the Xitiaoxi River Basin (XRB). Two future land-use conditions, projected by CA-Markov model, and 21 climate scenarios, downscaled from three general circulation models, are considered. The results show that urban area would expand dramatically from 4.4% to 12.63%, which mainly occupy the forest-grass and agriculture land. The LUCC will decrease low flow index as well as increase high flow index, annual maximum 1-day and 5-day streamflow. Extreme precipitation indices all exhibit trends toward an increase in future occurrence. Furthermore, in testing the response of extreme hydrological events to climate change, most extreme hydrological indices are predicted to become greater than they were throughout the 1970s. The combined effects of LUCC and climate change would increase all extreme hydrological indices. Moreover, the climate change would contribute >50% of these hydrological impacts. These findings indicate that the XRB will experience more severe extreme hydrological events in both flooding and drought due to climate and land-use change. It is advised that disaster mitigation measures must be updated accordingly to respond to this changing situation.

The Impact of Land Use/Land Cover Change (LULCC) on Water Resources in a Tropical Catchment in Tanzania under Different Climate Change Scenarios

Many parts of sub-Saharan Africa (SSA) are prone to land use and land cover change (LULCC). In many cases, natural systems are converted into agricultural land to feed the growing population. However, despite climate change being a major focus nowadays, the impacts of these conversions on water resources, which are essential for agricultural production, is still often neglected, jeopardizing the sustainability of the socio-ecological system. This study investigates historic land use/land cover (LULC) patterns as well as potential future LULCC and its effect on water quantities in a complex tropical catchment in Tanzania. It then compares the results using two climate change scenarios. The Land Change Modeler (LCM) is used to analyze and to project LULC patterns until 2030 and the Soil and Water Assessment Tool (SWAT) is utilized to simulate the water balance under various LULC conditions. Results show decreasing low flows by 6–8% for the LULC scenarios, whereas high flows increase by up to 84% for the combined LULC and climate change scenarios. The effect of climate change is stronger compared to the effect of LULCC, but also contains higher uncertainties. The effects of LULCC are more distinct, although crop specific effects show diverging effects on water balance components. This study develops a methodology for quantifying the impact of land use and climate change and therefore contributes to the sustainable management of the investigated catchment, as it shows the impact of environmental change on hydrological extremes (low flow and floods) and determines hot spots, which are critical for environmental development.

Land use/land cover changes and its impact on ecosystem services in ecologically fragile zone: A case study of Zhangjiakou City, Hebei Province, China

Abstract Land use/land cover (LULC) changes are likely to become more frequent and intense as a result of anthropogenic activities and may significantly affect human welfare by modifying ecosystem services (ESs). Understanding the impact of LULC changes on ESs value and the interactions among ESs could result in improvements in current land use policies and provide a scientific basis for the formulation of new policies in ecologically fragile zones. A case study was conducted in Zhangjiakou City, which is considered a typical ecologically fragile mountainous area in China, to examine the effects of LULC changes on ESs value and the interactions among ESs, including carbon sequestration and oxygen production (CSOP), water yield (WY), soil conservation (SC), sand-fixing (SF), and agricultural production (AP) from 2000 to 2015. Our results showed that ESs in Zhangjiakou City benefited substantially from existing land use policies and their “win-win expectations.” There were dramatic changes in the LULC types over the study period, especially in forestland, grassland, and arable land, with a significant impact on ESs value. LULC changes resulted in a significant increase in ESs value (US$ 3147.44 million), with the maximum increase occurring in AP (US$ 2255.19 million). However, LULC significantly decreased the value of the WY by $61.91 million, which mainly resulted from the degradation of arable land, forestland, and grassland. Strong trade-off relationships between WY and SC, CSOP and SC, SC and SF, and SC and AP were observed in 2000. Trade-off relationships were markedly weaken by LULCCs but increased by human activities when related to AP. Finally, a new spatialization approach of AP was designed and quantitative method of trade-off index was improved based on economic value. These results could offer some suggestions for land space optimization and ecological construction in Zhangjiakou City as well as in the similar regions in China, and provide some scientifically basis on the research area of coordination development of multi-functions of land use or geographical functions.

Impact of land use and land cover transitions and climate on evapotranspiration in the Lake Naivasha Basin, Kenya

The Lake Naivasha Basin in Kenya has experienced significant land use cover changes (LUCC) that has been hypothesized to have altered the hydrological regime in recent decades. While it is generally recognized that LUCC will impact evapotranspiration (ET), the precise nature of such impact is not very well understood. This paper describes how land use conversions among grassland and croplands have influenced ET in the Lake Naivasha Basin for the period 2003 to 2012. MODIS data products were used in combination with the European Centre for Medium-Range Weather Forecasts (ECMWF) data sets to model ET using the Surface Energy Balance System (SEBS). The results indicate that conversions from grassland to cropland accounted for increases in ET of up to 12% while conversion from cropland back to grasslands (abandonment) reduced ET by ~4%. This suggests that recently cultivated agricultural lands could increase local water demands, while abandonment of the farms could decrease the water loss and eventually increase the water availability. Also, recovery of ET following re-conversion from cropland to grassland might be impeded due to delayed recovery of soil properties since parts of the catchment are continuously being transformed with no ample time given for soil recovery. The annual ET over the 10 years shows an estimated decline from 724 mm to 650 mm (~10%). This decline is largely explained by a reduction in net radiation, an increase in actual vapour pressure whose net effect also led to decrease in the surface-air temperature difference. These findings suggest that in order to better understand LUCC effects on water resources of Lake Naivasha, it is important to take into account the effect of LUCC and climate because large scale changes of vegetation type from grassland to cropland substantially will increase evapotranspiration with implications on the water balance.

Land Use/Cover Change Effects on River Basin Hydrological Processes Based on a Modified Soil and Water Assessment Tool: A Case Study of the Heihe River Basin in Northwest China’s Arid Region

Land use/cover change (LUCC) affects canopy interception, soil infiltration, land-surface evapotranspiration (ET), and other hydrological parameters during rainfall, which in turn affects the hydrological regimes and runoff mechanisms of river basins. Physically based distributed (or semi-distributed) models play an important role in interpreting and predicting the effects of LUCC on the hydrological processes of river basins. However, conventional distributed (or semi-distributed) models, such as the soil and water assessment tool (SWAT), generally assume that no LUCC takes place during the simulation period to simplify the computation process. When applying the SWAT, the subject river basin is subdivided into multiple hydrologic response units (HRUs) based on the land use/cover type, soil type, and surface slope. The land use/cover type is assumed to remain constant throughout the simulation period, which limits the ability to interpret and predict the effects of LUCC on hydrological processes in the subject river basin. To overcome this limitation, a modified SWAT (LU-SWAT) was developed that incorporates annual land use/cover data to simulate LUCC effects on hydrological processes under different climatic conditions. To validate this approach, this modified model and two other models (one model based on the 2000 land use map, called SWAT 1; one model based on the 2009 land use map, called SWAT 2) were applied to the middle reaches of the Heihe River in northwest China; this region is most affected by human activity. Study results indicated that from 1990 to 2009, farmland, forest, and urban areas all showed increasing trends, while grassland and bare land areas showed decreasing trends. Primary land use changes in the study area were from grassland to farmland and from bare land to forest. During this same period, surface runoff, groundwater runoff, and total water yield showed decreasing trends, while lateral flow and ET volume showed increasing trends under dry, wet, and normal conditions. Changes in the various hydrological parameters were most evident under dry and normal climatic conditions. Based on the existing research of the middle reaches of the Heihe River, and a comparison of the other two models from this study, the modified LU-SWAT developed in this study outperformed the conventional SWAT when predicting the effects of LUCC on the hydrological processes of river basins.

Spatio-temporal analysis of land use/land cover change and its effects on soil erosion (Case study in the Oplenac wine-producing area, Serbia).

In this paper, various spatial modelling techniques were applied to analyse changes in soil cover and their impact on soil erosion in the Oplenac wine-producing area in Serbia in the past (1985 and 2013) and in the future (with predictions for 2041). The Integrated Valuation of Ecosystem Services and Trade-offs Sediment Delivery Ratio (InVEST SDR) model and the Modules for Land Use Change Evaluation (MOLUSCE) model, integrated with methods of remote sensing, were successfully applied and were shown to be valid tools for predicting the impact of Land Use Land Cover (LULC) changes when estimating soil loss. The results revealed that the greatest impact of land use changes between 1985 and 2013 was on a reduction in areas under vineyards and an extension of meadow and pasturelands as an individual and social response to economic conditions during the research period. The forecast for 2041 reflected the trends observed in the previous period, with the greatest changes witnessing an increase in urban areas and a decrease in areas of arable land. It was also found that the effect of LULC changes on spatio-temporal patterns in the Oplenac wine-producing area did not have a major impact on soil loss, meaning this area, with its good agro-climatic characteristics, is suitable for the intensification of agricultural production.

Scale-dependent impacts of urban and agricultural land use on nutrients, sediment, and runoff

We coupled a spatially-explicit land use/land cover (LULC) change model, Dinamica EGO, (Environment for Geoprocessing Objects), with the Chesapeake Bay Watershed Model (CBWM) to project the impact of future LULC change on loading of total nitrogen (TN), total phosphorous (TP) and total suspended solids (TSS) as well as runoff volume in the watersheds surrounding Virginia's Shenandoah National Park in the eastern United States. We allowed for the dynamic transition of four LULC classes, Developed, Forest, Grasses (including both pasture and hayfields) and Crops. Using 2011 as a baseline scenario and observed differences in LULC between 2001 and 2011, we estimated the temporal and spatial patterns of LULC change as influenced by physiographic and socio-economic drivers 50 years in the future (2061). Between transitions of the four LULC classes, the greatest absolute change occurred between the gain in total Developed land and loss in total Forest. New Developed land was driven primarily by distance to existing Developed land and population density. Major findings on the effect of LULC change on watershed model outputs were that: the impact of LULC change on pollutant loading and runoff volume is more pronounced at finer spatial scales; increases in the area of Grasses produced the greatest increase in TP loading, while loss of Forest increased TN, TSS, and runoff volume the most; and land-river segments with a greater proportion of Developed or a smaller proportion of Forest in the 2011 scenario experienced a greater change in runoff than other land-river segments. Results of this study illustrate the potential impact of projected LULC change on nutrient and sediment loads which can adversely impact water quality. Studies like this contribute to a broader understanding of how ecosystem services such as fresh water respond to LULC change, information relevant to those in planning and watershed management.

Woody encroachment and soil carbon stocks in subalpine areas in the Central Spanish Pyrenees

Woody encroachment has been an ongoing process in the subalpine belt of Mediterranean mountains, after land abandonment, the disappearance of the transhumant system and the decrease of the livestock number. The main objectives of this study were: (i) to identify land use/land cover (LULC) changes from 1956 to 2015, and (ii) to investigate the effects of LULC changes in physical and chemical soil properties and soil organic carbon (SOC) and nitrogen (N) stocks. It is hypothesized that woody encroachment in the subalpine belt may lead to significant changes in soil properties, and will generate an increase in the SOC stocks. A land use gradient was identified in the subalpine belt of the Central Spanish Pyrenees: (i) subalpine grasslands, (ii) shrublands, (iii) young forests, and (iv) old forests. Mineral soil samples were collected every 10 cm, down to 40 cm, at three points per each LULC and a total of 48 samples were analyzed. The results showed that (i) woody encroachment has occurred from 1956 to 2015 due to the expansion of coniferous forests and shrublands (at the expense of grasslands), (ii) land cover and soil depth had significant effects on soil properties (except for pH), being larger in the uppermost 0–10 cm depth, (iii) SOC and N contents and stocks were higher in the grassland sites, and (iv) the woody encroachment process initially produced a decrease in the SOC stocks (shrublands), but no differences were observed considering the complete soil profile between grasslands and young and old forests. Further studies, describing SOC stabilization and quantifying above-ground carbon (shrub and tree biomass) are required.

Long-Term Hydrologic Impact Assessment of Non-point Source Pollution Measured Through Land Use/Land Cover (LULC) Changes in a Tropical Complex Catchment

The contribution of non-point source pollution (NPS) to the contamination of surface water is an issue of growing concern. Non-point source (NPS) pollutants are of various types and altered by several site-specific factors making them difficult to control due to complex uncertainties involve in their behavior. Kelantan River basin, Malaysia is a tropical catchment receiving heavy monsoon rainfall coupled with intense land use/land cover (LULC) changes making the area consistently flood prone thereby deteriorating the surface water quality in the area. This study was conducted to determine the spatio-temporal variation of NPS pollutant loads among different LULC changes and to establish a NPS pollutant loads relationships among LULC conditions and sub-basins in each catchment. Four pollutants parameters such as total suspended solids (TSS), total phosphorus (TP), total nitrogen (TN) and ammonia nitrogen (AN) were chosen with their corresponding event mean concentration values (EMC). Soil map and LULC change maps corresponding to 1984, 2002 and 2013 were used for the calculation of runoff and NPS pollutant loads using numeric integration in a GIS environment. Analysis of Variance (ANOVA) was conducted for the comparison of NPS pollutant loads among the three LULC conditions used and the sub-basins in each catchment. The results showed that the spatio-temporal variation of pollutant loads in almost all the catchments increased with changes in LULC condition as one moves from 1984 to 2013, with 2013 LULC condition found as the dominant in almost all cases. NPS pollutant loads among different LULC changes also increased with changes in LULC condition from 1984 to 2013. While urbanization was found to be the dominant LULC change with the highest pollutant load in all the catchments. Results from ANOVA reveals that statistically most significant (p < 0.05) pollutant loads were obtained from 2013 LULC conditions, while statistically least significant (p < 0.05) pollutant loads were obtained under 1984 LULC condition. This reveals the clear effect of LULC changes on NPS pollution. The findings of this study may be useful to water resource planners in controlling water pollution for future planning.

Land-Surface Characteristics and Climate in West Africa: Models’ Biases and Impacts of Historical Anthropogenically-Induced Deforestation

Land Use Land-Cover Change (LULCC), such as deforestation, affects the climate system and land-atmosphere interactions. Using simulations carried out within the LUCID (Land Use and Climate, IDentification of robust Impacts) project framework, we first quantify the role of historical land-cover change induced by human activities on surface climate in West Africa. Focusing on two contrasted African regions, we find that climate responses of land-use changes are small but they are still statistically significant. In Western Sahel, a statistically significant near-surface atmospheric cooling and a decrease in water recycling are simulated in summer in response to LULCC. Over the Guinean zone, models simulate a significant decrease in precipitation and water recycling in autumn in response to LULCC. This signal is comparable in magnitude with the effect induced by the increase in greenhouse gases. Simulated climate changes due to historical LULCC could however be underestimated because: (i) the prescribed LULCC can be underestimated in those regions; (ii) the climate models underestimate the coupling strength between West African surface climate and leaf area index (LAI) and (iii) the lack of interactive LAI in some models. Finally, our study reveals indirect atmospheric processes triggered by LULCC. Over the Western Sahel, models reveal that a significant decrease in solar reflection tend to cool down the surface and thus counteract the atmospheric feedback. Conversely, over the Guinea zone, models reveal that the indirect atmospheric processes and turbulent heat fluxes dominate the climatic responses over the direct effects of LULCC.

Quantifying the effects of LUCCs on local temperatures, precipitation, and wind using the WRF model.

Land use/cover changes (LUCCs) are an important cause of regional climate changes, but the contribution of LUCCs to regional climate changes is not clear. In this study, the Weather Research and Forecasting (WRF) model and statistical methods were used to investigate changes in meteorologic variables in January, April, July, and October 2013 due to local LUCCs from 1990 to 2010 in southern Shandong province, China. The results indicate that the WRF model simulates temperatures in the region well, with high correlation coefficients (0.86-0.97, p<0.001) between the modeled and measured values. The model simulates precipitation less well, with correlation coefficients of 0.41-0.91, but they are all at statistically significant levels, with p<0.05. During the 20-year period, the LUCCs in the study area consisted mainly of conversions from dry land to urbanized land (747.3km2) and bare/sparse vegetation (132.4km2). The LUCCs caused a 0.16°C temperature increase in January and October and 0.01 and 0.18°C temperature decreases in April and July, respectively. The range of temperature changes over mixed forest and water bodies due to the LUCCs was wide (0.39-1.31°C) and was narrower over deciduous broadleaf forest and wetland (0.01 to 0.06°C). The LUCCs did not change the precipitation greatly in January, April, and October but did affect the precipitation in July substantially, causing a decrease of 23.71mm. The LUCCs did not affect wind speed and direction substantially during these four months: average wind speeds increased by 0.02 and 0.01m/s in January and October, respectively, and decreased by 0.02 and 0.05m/s in April and July, respectively. Overall, The LUCCs affected spring temperatures the least and summer precipitation the most.

Spatio-temporal patterns of the effects of precipitation variability and land use/cover changes on long-term changes in sediment yield in the Loess Plateau, China

Abstract. Within China's Loess Plateau there have been concerted revegetation efforts and engineering measures since the 1950s aimed at reducing soil erosion and land degradation. As a result, annual streamflow, sediment yield, and sediment concentration have all decreased considerably. Human-induced land use/cover change (LUCC) was the dominant factor, contributing over 70 % of the sediment load reduction, whereas the contribution of precipitation was less than 30 %. In this study, we use 50-year time series data (1961–2011), showing decreasing trends in the annual sediment loads of 15 catchments, to generate spatio-temporal patterns in the effects of LUCC and precipitation variability on sediment yield. The space–time variability of sediment yield was expressed notionally as a product of two factors representing (i) the effect of precipitation and (ii) the fraction of treated land surface area. Under minimal LUCC, the square root of annual sediment yield varied linearly with precipitation, with the precipitation–sediment load relationship showing coherent spatial patterns amongst the catchments. As the LUCC increased and took effect, the changes in sediment yield pattern depended more on engineering measures and vegetation restoration campaign, and the within-year rainfall patterns (especially storm events) also played an important role. The effect of LUCC is expressed in terms of a sediment coefficient, i.e., the ratio of annual sediment yield to annual precipitation. Sediment coefficients showed a steady decrease over the study period, following a linear decreasing function of the fraction of treated land surface area. In this way, the study has brought out the separate roles of precipitation variability and LUCC in controlling spatio-temporal patterns of sediment yield at catchment scale.

Mapping the Influence of Land Use/Land Cover Changes on the Urban Heat Island Effect—A Case Study of Changchun, China

The spatio-temporal patterns of land use/land cover changes (LUCC) can significantly affect the distribution and intensity of the urban heat island (UHI) effect. However, few studies have mapped a clear picture of the influence of LUCC on UHI. In this study, both qualitative and quantitative models are employed to explore the effect of LUCC on UHI. UHI and LUCC maps were retrieved from Landsat data acquired from 1984, 1992, 2000, 2007, and 2014 to show their spatiotemporal patterns. The results showed that: (1) both the patterns of LUCC and UHI have had dramatic changes in the past 30 years. The urban area of Changchun increased more than four times, from 143.15 km2 in 1984 to 577.45 km2 in 2014, and the proportion of UHI regions has increased from 15.27% in 1984 to 29.62% in 2014; (2) the spatiotemporal changes in thermal environment were consistent with the process of urbanization. The average LST of the study area has been continuously increasing as many other land use types have been transformed to urban regions. The mean temperatures were higher in urban regions than rural areas over all of the periods, but the UHI intensity varied based on different measurements; and (3) the thermal environment inside the city varied widely even within a small area. The LST possesses a very strong positive relationship with impervious surface area (ISA), and the relationship has become stronger in recent years. The UHI we employ, specifically in this study, is SUHI (surface urban heat island).

Identifying separate impacts of climate and land use/cover change on hydrological processes in upper stream of Heihe River, Northwest China

AbstractClimate change and land use/cover change (LUCC) are two factors that produce major impacts on hydrological processes. Understanding and quantifying their respective influence is of great importance for water resources management and socioeconomic activities as well as policy and planning for sustainable development. In this study, the Soil and Water Assessment Tool (SWAT) was calibrated and validated in upper stream of the Heihe River in Northwest China. The reliability of the SWAT model was corroborated in terms of the Nash–Sutcliffe efficiency (NSE), the correlation coefficient (R), and the relative bias error (BIAS). The findings proposed a new method employing statistical separation procedures using a physically based modeling system for identifying the individual impacts of climate change and LUCC on hydrology processes, in particular on the aspects of runoff and evapotranspiration (ET).The results confirmed that SWAT was a powerful and accurate model for diagnosis of a key challenge facing the Heihe River Basin. The model assessment metrics, NSE, R, and BIAS, in the data were 0.91%, 0.95%, and 1.14%, respectively, for the calibration period and 0.90%, 0.96%, and −0.15%, respectively, for the validation period. An assessment of climate change possibility showed that precipitation, runoff, and air temperature exhibited upward trends with a rate of 15.7 mm, 6.1 mm, and 0.38 °C per decade for the 1980 to 2010 period, respectively. Evaluation of LUCC showed that the changes in growth of vegetation, including forestland, grassland, and the shrub area have increased gradually while the barren area has decreased. The integrated effects of LUCC and climate change increased runoff and ET values by 3.2% and 6.6% of the total runoff and ET, respectively. Climate change outweighed the impact of LUCC, thus showing respective increases in runoff and ET of about 107.3% and 81.2% of the total changes. The LUCC influence appeared to be modest by comparison and showed about −7.3% and 18.8% changes relative to the totals, respectively. The increase in runoff caused by climate change factors is more than the offsetting decreases resulting from LUCC. The outcomes of this study show that the climate factors accounted for the notable effects more significantly than LUCC on hydrological processes in the upper stream of the Heihe River.

Land-use/land-cover change and ecosystem service provision in China

As a result of economics and policy, land-use/land-cover change (LUCC) in China has undergone a series of complicated changes over the past three decades. However, the effects of LUCCs on ecosystem service values (ESVs) have never been previously assessed at the national scale. Thus, on the basis of three Chinese LUCC maps from 1988, 2000, and 2008, we examined changes in land-use/land-cover and consequent ESVs using a value transfer method. We found that ESVs decreased by 0.45% and 0.10% during the periods 1988–2000 and 2000–2008, respectively, and that ESV changes in China during the period 2000–2008 were relatively moderate compared to the rest of the world over a similar period. The ESVs for provision, regulation, support, and culture decreased by 0.19%, 0.48%, 0.43%, and 0.45%, respectively, during the period 1988–2000, while they decreased by 0.11%, 0.09%, 0.14%, and 0.04%, respectively, during the period 2000–2008. We also developed an elasticity indicator to assess responses in ESV change relative to LUCCs. Results of this analysis show that 1% of land conversion in China resulted in 0.15% and 0.10% average changes in ESVs during the two periods, respectively.