GIS and L-THIA Based Analysis on Variations of Non-point Pollution in Nansi Lake Basin,China

Non-point source(NPS) pollution is the main threat to regional water quality,and the estimation of NPS pollution load has become an important task for NPS pollution control in China.Combined with geographical information system(CIS),the longterm hydrologic impact assessment(L-THIA) model was used to evaluate the temporal-spatial changes of chemical oxygen demand(COD),total nitrogen(TN) and total phosphorus(TP) in Nansi Lake basin from 2000 to 2010.The results show:1) the estimated COD,TN and TP loads in 2010 are260017.5,111607.7 and 6372.0 t with the relative errors of 2.1%,2.0%and-8.8%respectively,and more than 90%concentrated in the raining period from June to September;2) cultivated land and construction land take up more than 80%of the whole Nansi Lake basin,and the proportions of the three kinds of NPS pollution loads coming from cultivated land and construction land are more than 98%;3) during 2000-2010,the COD,TN and TP loads increase by 8801.6,180.3 and 71.9 t respectively,and become the main impact factors on the water quality of Nansi Lake.

Evidence for a recent warming and wetting in the source area of the Yellow River （SAYR） and its hydrological impacts

Climate change investigation at a watershed-scale plays a significant role in re- vealing the historical evolution and future trend of the runoff variation in watershed. This study examines the multisource hydrological and meteorological variables over the source area of the Yellow River （SAYR） from 1961 to 2,012 and the future climate scenarios in the region during 2006-2100 based on the CMIP5 projection data. It recognizes the significant charac-teristics of the recent climate change in the SAYR and predicts the change trend of future flow in the region. It is found that （1） The climate in the SAYR has experienced a significant warm-wet change since the early 2000s, which is very different from the antecedent warm-dry trend since the late 1980s; （2） The warm-wet trend in the northwestern SAYR （the headwater area of the Yellow River （HAYR）, is more obvious than that in the whole SAYR; （3） With pre- cipitation increase, the runoff in the region also experienced an increasing process since 2006. The runoff variations in the region are sensitive to the changes of precipitation, PET and maximum air temperature, but not very sensitive to changes in mean and minimum air temperatures; （4） Based on the CMIP5 projection data, the warm-wet climate trend in SAYR are likely to continue until 2049 if considering three different （i.e. RCP2.6, RCP4.5 and RCP8.5） greenhouse gas emission scenarios, and the precipitation in SAYR will not be less than the current level before 2100; however, it is estimated that the recent flow increase in the SAYR is likely to be the decadal change and it will at most continue until the 2020s; （5） The inter-annual variations of the East Asian winter monsoon are found to be closely related to the variations of annual precipitation in the region. Meanwhile, the increased precipitation as well as the increase of potential evapotranspiration （PET） being far less than that of precipitation in the recent period are the main climate causes for the flow increase in the region.

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.

Method to assess water footprint,a case study for white radishes in Korea

This study aimed to assess the water footprint of white radishes which is cultivated during four seasons.The methodology is developed in accordance with ISO 14040s and ISO 14046.This study suggested the water depletion and eutrophication results of white radishes as water footprint results.The water de-pletion results are 25.58 m^(3) fres hwater/ton(spring season white radish),20.74 m^(3) freshwater/ton(au-tumn season white radish),26.68 m^(3) freshwater/ton(alpine region white radish),and 2856 m^(3) fresh-water/ton(facility white radish),respectively.And the eutrophication results are 3.23E-11 kg P/ton(spring season white radish),2.66E-11 kg P/ton(autumn season white radish),3.94E-11 kg P/ton(alpine region white radish),and 1.56E-11 kg P/ton(facility white radish),respectively.In conclusion,autumn season white radish is more competitive than other cultivation types in the context of water footprint assessment.As a result,switching from other cultivation types to autumn season white radish is ex-pected to offer a more water-efficient means of white radish cultivation.Henceforth,drawing upon evidence within this report,decision-makers would be wise to cultivate in more effective water use cultivation type and crop species.