Application of Land-use Change Model in Guiding Regional Planning:A Case Study in Hun-Taizi River Watershed,Northeast China

This paper firstly investigated the land-use and land-cover change （LUCC） in the Hun-Taizi River water- shed, Northeast China from 1988 to 2004 based on remotely sensed images and geographic information systems （GIS） technology. Then, using the famous land-use change model of Conversion of Land Use and its Effects at Small re- gional extent （CLUE-S）, this paper simulated the land use changes under historical trend （HT）, urban planning （UP） and ecological protection （EP） scenarios considering urban planning and ecological protection over the next 20 years. The simulated results under UP scenario in 2020 were compared with the planning map to assess the feasibility of us- ing land-use change model to guide regional planning. Results show that forest land, dry farmland, paddy, and shrub land were the main land-use categories. Paddy and dry farmland being converted to urban area and rural settlement characterized the land-use change from 1988 to 2004. The main land-use categories changed over time. Landscape-pattem fragmentation will be worse under HT and UP scenarios, but better in EP scenario. The comparing results of simulated map with planning map in 2020 show that land-use change model is powerful tool to guide regional planning. Land-use scenarios can support regional planning and policy-making through analyzing future consequences scientifically.

Functional Rehabilitation of the "Soil Reservoir"in Degraded Soils to Control Floods in the Yangtze River Watershed

The reasons for the Yangtze River flood calamity in 1998 are briefly introduced. The authors believe that using a 'soil reservoir' concept is an important means to help control flooding of the Yangtze River.A 'soil reservoir' has a large potential storage capacity and its water can be rapidly 'discharged' into the underground water in a timely fashion. The eroded, infertile soils of the Yangtze River Watershed are currently an obstacle to efficient operation of the 'soil reservoir'. The storage capacity of this 'soil reservoir'has been severely hampered due to intensive soil erosion and the formation of soil crusts. Therefore, possible measures to control floods in the Yangtze River Watershed include: rehabilitating the vegetation to preserve soil and water on the eroded infertile soils, enhancing infiltration of the different soil types, and utilizing the large 'soil reservoir' of the upper reaches of the Yangtze River.

Impact of climate factors on runoff in the Kaidu River watershed:path analysis of 50-year data

Runoff formation is a complex meteorological-hydrological process impacted by many factors,especially in the inland river basin.Based on the data of daily mean air temperature,precipitation and runoff during the period of 1958-2007 in the Kaidu River watershed,this paper analyzed the changes in air temperature,precipitation and runoff and revealed the direct and indirect impacts of daily air temperature and precipitation on daily runoff by path analysis.The results showed that mean temperature time series of the annual,summer and autumn had a significant fluctuant increase during the last 50 years（P 0.05）.Only winter precipitation increased significantly（P 0.05） with a rate of 1.337 mm/10a.The annual and winter runoff depthes in the last 50 years significantly increased with the rates of 7.11 mm/10a and 1.85 mm/10a,respectively.The driving function of both daily temperature and precipitation on daily runoff in annual and seasonal levels is significant in the Kaidu River watershed by correlation analysis.The result of path analysis showed that the positive effect of daily air temperature on daily runoff depth is much higher than that of daily precipitation in annual,spring,autumn and winter,however,the trend is opposite in summer.

Spatial distribution of soil moisture,salinity and organic matter in Manas River watershed,Xinjiang,China

With the classical statistical and geostatistical methods, the study of the spatial distribution and its in- fluence factors of soil water, salinity and organic matter was carried out for 0-70 cm soil layers in Manas River watershed. The results showed that the soil moisture data from all soil layers exhibited a normal distribution, with average values of 14.08%-21.55%. Geostatistical analysis revealed that the content of soil moisture had a moder- ate spatial autocorrelation with the ratios of nugget/sill ranging from 0.500 to 0.718, which implies that the spatial pattern of soil moisture is influenced by the combined effects of structural factors and random factors. Remarkable spatial distributions with stripped and mottled features were found for soil moisture in all different soil layers. The landform and crop planting had a relatively big influence on the spatial distribution of soil moisture; total soil salinity was high in east but low in west, and non-salinized soil and lightly salinized soil appeared at the northwest and southwest of the study area. Under the effect of reservoir leakage, the heavily salinized soils are widely distributed in the middle of the study area. The areas of the non-salinized and lightly salinized soils decreased gradually with soil depth increment, which is contrary to the case for saline soils that reached a maximum of 245.67 km2 at the layer of 50-70 cm. The types of soil salinization in Manas River watershed were classified into four classes： the sulfate, chloride-sulfate, sulfate-chloride and chloride. The sulfate salinized soil is most widely distributed in the surface layer. The areas of chloride-sulfate, sulfate-chloride, and chloride salinized soils increased gradually along with the increment of soil depth; the variation range of the average values of soil organic matter content was be- tween 7.48%-11.33%. The ratios of nugget/sill reduced gradually from 0.698 to 0.299 with soil depth increment, which shows that the content of soil organic matter has a moderate spatial autocorrelation. The soil organic matter in all soil layers met normal distribution after logarithmic transformation. The spatial distribution patterns of soil or- ganic matter and soil moisture were similar; the areas with high organic matter contents were mainly distributed in the south of the study area, with the lowest contents in the middle.

Understanding the impact of mountain landscapes on water balance in the upper Heihe River watershed in northwestern China

Estimating the impact of mountain landscape on hydrology or water balance is essential for the sus- tainable development strategies of water resources. Specifically, understanding how the change of each landscape influences hydrological components will greatly improve the predictability of hydrological responses to mountain landscape changes and thus can help the government make sounder decisions. In the paper, we used the VIC （Variable Infiltration Capacity） model to conduct hydrological modeling in the upper Heihe River watershed, along with a frozen-soil module and a glacier melting module to improve the simulation. The improved model performed satisfactorily. We concluded that there are differences in the runoff generation of mountain landscape both in space and time. About 50% of the total runoff at the catchment outlet were generated in mid-mountain zone （2,900-4,000 m asl）, and water was mainly consumed in low mountain region （1,700-2,900 m asl） because of the higher requirements of trees and grasses. The runoff coefficient was 0.37 in the upper Heihe River watershed. Barren landscape produced the largest runoff yields （52.46% of the total runoff） in the upper Heihe River watershed, fol- lowed by grassland （34.15%）, shrub （9.02%）, glacier （3.57%）, and forest （0.49%）. In order to simulate the impact of landscape change on hydrological components, three landscape change scenarios were designed in the study. Scenario 1, 2 and 3 were to convert all shady slope landscapes at 2,000-3,300 m, 2,000-3,700 m, and 2,000-4,000 m asl respectively to forest lands, with forest coverage rate increased to 12.4%, 28.5% and 42.0%, respectively. The runoff at the catchment outlet correspondingly declined by 3.5%, 13.1% and 24.2% under the three scenarios. The forest landscape is very important in water conservation as it reduced the flood peak and increased the base flow. The mountains as ＂water towers＂ play important roles in water resources generation and the impact of mountain landscapes on hydrology is significant.

Livelihood Strategy Change and Land Use Change——Case of Danzam Village in Upper Dadu River Watershed,Tibetan Plateau of China

Land use change in rural China since the 1980s, induced by institution reforms, urbanization, industrialization and population increase, has received more attention. However, case studies on how institution reforms affect farmers＇ livelihood strategies and drive land use change are scarce. By means of cropland plots investigations and interviews with farmers, this study examines livelihood strategy change and land use change in Danzam Village of Jinchuan County in the upper Dadu River watershed, eastern Tibetan Plateau, China. The results show that, during the collective system period, as surplus labor forces could not be transferred to the secondary and tertiary industries, they had to choose agricultural involution as their livelihood strategy, then the farmers had to produce more grains by land reclamation, increasing multiple cropping index, improving input of labor, fertilizer, pesticide and adopting advanced agricultural techniques. During the household responsibility system period, as labors being transferred to the secondary and tertiary industries, farmers chose livelihood diversification strategy. Therefore, labor input to grain planting was greatly reduced, which drove the transformation of grain to horticulture, vegetable or wasteland and decrease of multiple cropping index. This study provides a new insight into understanding linkages among institution reforms, livelihood strategy of smallholders and land use change in rural China.

Oasis System and Its Reasonable Development in Sangong River Watershed in North of the Tianshan Mountains,Xinjiang,China

Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources structure, vegetation structure, economic structure and their corresponding functions. The results indicate that as a typical small-scale watershed, Sangong River watershed has the relatively complete mountain-basin structure, and ecological and productive function. Because of human drastic activity the utilization rate of water resources was as high as 98.7%, and the utilization of groundwater was not reasonable, which resulted in an average annual decline of 0.353m in the water table of alluvial-diluvial-fan oasis, and an average annual increase of 0.047m in the alluvial-plain. The layout of crop and shelter forest benefits to the utilization of water and land resources. The development of oasis economy is at low level, and its eco-economic function is weak.

Soil and water loss in the Lancang River-Mekong River watershed (in Yunnan section, China) and its control measures

According to a lot of hydrological and environmental monitoring data, the condition of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is described. The occurrence and development of soil and water loss is analyzed. The conclusion is that: (1) generally, the situation of soil and water loss in the Lancang River Mekong River watershed (in Yunnan section, China) is light, however, soil and water loss in some regions is serious, especially in the middle reach area of the river; (2) soil and water loss in the Lancang River Mekong River (in Yunnan section, China) watershed presents developing tendency and it is mainly caused by human beings. In accordance with these results, the control measures for soil and water loss are discussed.

RELATION BETWEEN PRECIPITATION AND SEDIMENT TRANSPORT IN THE DASHA RIVER WATERSHED

The study on sediment production and its relationship with climatic and hydrological factors in watershed is a major environment issue of concern in the international community. Based on the observational records covering the period from 1954 to 1999, the characteristics of precipitation changing over the Dasha River Watershed in Anhui Province and its relation to sediment yield were studied using tendency analysis and correlation analysis.Results showed that the precipitation of the Dasha River Watershed has high variability. In those 46 years, 34% of spring rainfall, 58% of summer rainfall and 30% of annual rainfall will be considered anomaly. The gray correlation analysis shows that sediment discharge correlates most closely with the frequency of the rainstorm with a daily precipitation above 100mm, secondly with the frequency of the rainstorm with a daily precipitation of 50-100mm, and thirdly with the number of rainy days. Their correlation coefficients are 0.98,0.90 and 0.85 respectively. In addition,the paper suggests the major countermeasures and methods for controlling of soil and water losses in this area.

Climate-induced Changes in Spring Maize Water Requirement in Xiliaohe River Watershed

Xiliaohe River watershed plays an important role in regional and national grain security.With the development of society and economy,water consumption that increased dramatically causes water shortages.Crop water requirement can provide quantitative basis for making regional irrigation scheme.In this study,spring maize water requirement is calculated by using PenmanMonteith formula and spring maize coefficient from May to September at 10 meteorological stations in Xiliaohe River watershed from 1951 to 2005.The variation trend of the spring maize water requirement during the whole growing stage,water requirement in every month,and meteorological influencing factors are obtained by using Mann-Kendall method,and the degree of grey incidence between the water requirement and meteorological influencing factors are shown.The results are the spring maize water requirement during the whole growing stages increases at half of the stations in Xiliaohe River watershed,and are remarkably affected by the water requirement in May.The monthly mean,maximum and minimum air temperature form May to September show an increasing trend in Xiliaohe River watershed in recent 55 years.The monthly mean and minimum air temperature increases notably.The relative humidity,precipitation,wind speed and sunshine show a decreasing trend with variety for different months.The monthly maximum air temperature,wind speed,sunshine and monthly mean air temperature have the highest correlation degree with spring maize water requirement from May to September.

Assessment of Institutional and Legal Framework for Sustainable Land Use Management Practices in Ashi River Watershed,China

Nonpoint source(NPS)pollutants resulting from land degradation(LD)have been a key influential factor on the deterioration of water quality.Consequently,sustainable land use management(SLM)practices have been employed to reduce the impacts of LD globally.However,the adoption of SLM practices is often not effective to protect water resources despite its capability of improving water quality.Empirically,evidence shows that activities of land users directly influence SLM practices and NPS pollution of water resources in watersheds,but invariably this has not been clearly understood.Understanding how SLM practices adoption could prevent NPS pollution of water resources in watershed is a necessity.Therefore,the primary aim of the investigation is to comprehend the status of SLM practices with the legal framework supporting the adoption of such practices in the Ashi River watershed.A survey instrument involving structured questionnaire was implemented to collect data.A randomly based lottery method was applied to sample information from 150 land users in two control units’communities.Descriptive and inferential statistics was used to analyze the data.This research revealed that there is low adoption of SLM practices of the study site.The low adoption is due to weak capacity building and enforcement of regulations in the watershed.Occupation and age of the residents are the strongest predictors of SLM adoption rate.Residents connected with farming are more sensitive to the adoption status of SLM.It is our recommendation that policy makers should ensure capacity building,and enforcement of regulations can specifically compel farmers to adopt SLM technologies.This approach would complement other strategies to solve the NPS pollution issue of Ashi River.

Centennial Analysis of Human Activity Intensity and Associated Historical Events in Heilongjiang River Sino-Russo Watershed

Human activities in a transborder watershed are complex under the influence of domestic policies,international relations,and global events.Understanding the forces driving human activity change is important for the development of transborder watershed.In this study,we used global historical land cover data,the hemeroby index model,and synthesized major historical events to analyze how human activity intensity changed in the Heilongjiang River(Amur River in Russia)watershed(HLRW).The results showed that there was a strong spatial heterogeneity in the variation of human activity intensity in the HLRW over the past century(1900-2016).On the Chinese side,the human activity intensity change shifted from the plain areas for agricultural reclamation to the mountainous areas for timber extraction.On the Russian side,human activity intensity changes mostly concentrated along the Trans-Siberian Railway and the Baikal-Amur Mainline.Localized variation of human activity intensity tended to respond to regional events while regionalized variation tends to reflect national policy change or broad international events.The similarities and differences between China and Russia in policies and positions in international events resulted in synchronous and asynchronous changes in human activity intensity.Meanwhile,policy shifts were often confined by the natural features of the watershed.These results reveal the historical origins and fundamental connotations of watershed development and contribute to formulating regional management policies that coordinate population,eco-nomic,social,and environmental activities.

Spatiotemporal variation and hotspots of climate change in the Yangtze River Watershed during 1958-2017

The Yangtze River Watershed in China is a climate change hotspot featuring strong spatial and temporal variability;hence, it poses a certain threat to social development. Identifying the characteristics of and regions vulnerable to climate change is significantly important for formulating adaptive countermeasures. However, with regard to the Yangtze River Watershed, there is currently a lack of research on these aspects from the perspective of natural and anthropogenic factors. To address this issue, in this study, based on the temperature and precipitation records from 717 meteorological stations, the RClim Dex and random forest models were used to assess the spatiotemporal characteristics of climate change and identify mainly the natural and anthropogenic factors influencing climate change hotspots in the Yangtze River Watershed for the period 1958-2017. The results indicated a significant increasing trend in temperature, a trend of wet and dry polarization in the annual precipitation, and that the number of temperature indices with significant variations was 2.8 times greater than that of precipitation indices. Significant differences were also noted in the responses of the climate change characteristics of the sub-basins to anthropogenic and natural factors;the delta plain of the Yangtze River estuary exhibited the most significant climate changes, where 88.89% of the extreme climate indices varied considerably. Furthermore, the characteristics that were similar among the identified hotpots, including human activities(higher Gross Domestic Product and construction land proportions) and natural factors(high altitudes and large proportions of grassland and water bodies), were positively correlated with the rapid climate warming.

Decreasing potential evapotranspiration in the Huanghe River Watershed in climate warming during 1960–2010

According to the meteorological observation data of 72 stations from 1960 to 2010 in the Huanghe （Yellow） River Watershed, China, the long-term variations of potential evapotranspiration, calculated in the modified Penman-Monteith model of Food and Agricul- ture Organization of the United Nations, were presented, as well as the meteorological causes for the decrease of potential evapotranspiration were discussed. Since 1960, temperature has risen significantly and potential evapotranspiration a decreasing trend, which indicated the existence of ＂Evaporation paradox＂ in the Huanghe River Watershed. This phenomenon was not consistent spatially or temporally with the increase of temperature, potential evapotranspiration decreased in spring, summer and winter, mainly over most parts of Shanxi and Henan, and some parts of Gansu, Ningxia, Inner Mongolia, and Shaanxi. During the recent half century, the trends of temperature and potential evapotranspiration were negatively correlated at most of the stations, while precipitation and potential evapotranspiration exhibited a contrary trend. Calculated in multiple regressions, the contribution to potential evapotranspiration change of related meteorological factors was discussed, including mean pressure, maximum and minimum temperature, sunshine hours, relative humidity and average wind speed. The decrease of wind speed in the Huanghe River Watershed may be the dominating factor causing potential evapotranspiration decreasing.

Integrated assessment and changes of ecological environment in the Daning River Watershed

Based on Remote Sensing(RS),Geographical Information Systems(GIS),and the Spatial Principal Compo-nent Analysis(SPCA)method,the integrated assessment and changes in the ecological environment of Daning River Watershed are studied in this paper.The watershed is located in the Three Gorge Area in China.The result of the integrated assessment showed that level 9 had the biggest proportion in the year 1990,which was about 40%.In the year 2000,however,there were no levels with a proportion significantly bigger than the others.By comparing the assessment results in 1990 and 2000,it is discovered that the ecological environ-ment in Daning River Watershed in 1990 was better than that in 2000.

SEFIDROOD RIVER SUB-WATERSHED-DAM-ESTUARY AND DEGRADATION MODEL:A HOLISTIC APPROACH IN IRAN

The major concern of this article is to address the shortcoming and outgoing effects of the human activities on the landscape patterns and their consequences in the Sefidrood River watershed in Iran. A flow of data includes three inputs; each of them belongs to one part of three zones of a fluvial system. The three parts of the Sefidrood River fluvial system include Zone 1,a sub-watershed as degradation modeling site,Zone 2,Sefidrood Dam as dam site,and Zone 3,17km away from the Sefidrood River path to the Caspian Sea as ending point site. The degradation model in the Zone 1 provides a suitable mean for decision support system to decrease the human impacts on each small district. The maximum number for degradation coefficient belongs to the small district with the highest physiographic density,relatively cumulative activities,and a lower figure for the habitat vulnerability. The human degradation impact were not limited to the upstream. The investigation to the Sefidrood Dam and ending point of the Sefidrood River depicts that sedimentation continues as a significant visual impact in the Sefidrood Dam reservoir and the estuary.

Impact of global climate change on stream low flows:A case study of the great Miami river watershed, Ohio, USA

Climate change will profoundly affect hydrological processes at various temporal and spatial scales.This study is focused on assessing the alteration of water resources availability and low flows frequencies driven by changing climates in different time periods of the 21st century.This study evaluates the adaptability of prevailing Global Circulation Models(GCMs)on a particular watershed through streamflow regimes.This analysis was conducted in the Great Miami River Watershed,Ohio by analyzing historical and future simulated streamflow using 10 climate model outputs and the Soil and Water Assessment Tool(SWAT).The climate change scenarios,consisting of ten downscaled Coupled Model Intercomparision Project Phase 5(CMIP5)climate models in combination with two Representative Concentration Pathways(RCP 4.5 and RCP 8.5)were selected based on the correlation between observed records and model outputs.Streamflow for three future periods,2016-2043,2044-2071 and 2072-2099,were independently analyzed and compared with the baseline period(1988-2015).Results from the average of ten models projected that 7-day low flows in the watershed would increase by 19%in the 21st century under both RCPs.This trend was also consistent for both hydrological(7Q10,1Q10)and biological low flow statistics(4B3,1B3).Similarly,average annual flow and monthly flows would also increase in future periods,especially in the summer.The flows simulated by SWAT in response to the majority of climate model projections showed a consistent increase in low flow patterns.However,the flow estimates using the Max-Planck-Institute Earth System Model(MPI-ESM-LR)climate output resulted in the biological based low flows(4B3,1B3)decreasing by 22.5%and 33.4%under RCP 4.5 and 56.9%and 63.7%under RCP 8.5,respectively,in the future when compared to the baseline period.Regardless,the low flow ensemble from the 10 climate models for the 21st century seemed to be slightly higher than that of historical low flows.

Long-term hydrological impacts of land use/land cover change from 1984 to 2010 in the Little River Watershed,Tennessee

Assessing long-term hydrological impacts of land use/land cover(LULC)change is of critical importance for land use planning and water resource management.The Little River Watershed,Tennessee,is an important watershed supporting drinking water and recreational activities within and around the Great Smoky Mountains National Park in the Unites States.However,the potential hydrological impacts of LULC change,especially urbanization in recent decades,are not quantified.This paper assessed the long-term impacts of LULC change on streamflow and non-point source pollution using the Soil and Water Assessment Tool(SWAT)and a detailed LULC record from 1984 to 2010.The SWAT was first calibrated and validated using observed streamflowin 2010 and then simulated using different LULC patterns in 1984-2010 to quantify the long-term hydrological impacts caused by the LULC change.Simulated results indicated a minor 3%increase in streamflow for the whole watershed from 1984 to 2010,but with a distinct spatial pattern.The increase in streamflow is closely related to urban development.Almost no streamflow increase occurred in the upper watershed within the national park,whereas>10%increase occurred in the lower watershed,especially in areas close to cities.Model simulation also suggested 34.6%reduction in sediment and about 10%reduction in nutrient loads from 1984 to 2010,closely related to the decrease in agricultural land.However,without calibration and validation,the simulated reduction in the sediment and nutrient loads may be problematic because SWAT mainly simulates the static LULC patterns,whereas LULC transitions,such as construction phases,may generate more sediment and nutrient loads.In addition,the simulation also did not account for the sediment and nutrients generated from stream bank erosion.

Analysis of the diet of the tadpole shrimp, Triops sinensis, in paddy fields of Shouchang River watershed

The tadpole shrimp,Triops sinensis,was discovered in the paddy fields of the Shouchang River watershed.The gut contents of the shrimp from these field populations were analyzed in order to quantify their dietary patterns.Some species of tadpole shrimps were found to prey on mosquito larvae as well as uproot weeds.Mosquito larvae and weeds were seldom found in the paddy fields which the tadpole shrimp inhabited in the Shouchang River watershed.The results further showed that the larvae of these tadpole shrimp mainly feed on algae and rice lamina.The tadpole shrimp could feed on animal food including protozoa,nematodes,rotifers,crustaceans,and aquatic insect larvae,though the animal food was subsidiary.

Geological Disaster Evaluation of the Xixi Watershed of the Jinjiang River Based on the Coupling of Landscape and Multiple Factors

Six evaluation factors were selected to evaluate the susceptibility level of the Xixi Watershed to geological disasters such as collapse and landslide, namely formation lithology, rainfall, gradient, aspect, vegetation and buffer zone. The results showed that Longmen Town, Gongqiao Town, Lianhua Town, and Chengxiang Town in the lower reaches of the Xixi Watershed were more susceptible to geological disasters in case of rainstorm because of the easily-collapsed formation lithology; riverbank erosion by runoff was enhanced during rainstorm, thus both sides of the rivers in Chengxiang Town at the estuary of the Xixi Watershed were most susceptible to geological disasters; in case of rainstorm, geological disaster monitoring in location areas of Longmen Town, Guanqiao Town, Lianhua Town, Chengxiang Town in the lower reaches, particularly trunk streams in Chengxiang Town, should be enhanced. By evaluating environmental geo-disasters of the Xixi Watershed, the blank in the environmental geo-disaster evaluation of the local area will be filled in, and scientific support will be provided for the future prevention of environmental geodisaster.