Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | and soil and sed- ff 1,2,4 ff Sciences Discussions Earth System Hydrology and and sediment load ff , and R. Li 3 8 (67 %) a decline in sed- ff ects can not only improve the ective land and water manage- ff ff and sediment load both showed a , C. Ritsema ff 2,4 and sediment load varied greatly during ff and soil loss were identified: 1951 to 1971 ected by climate change and human activi- ff ff 1214 1213 and sediment change in the Yan River Basin, ff , W. Zhang 3 ect were also studied. Five main findings emerged ff cients of variation that were much larger than those ffi , R. Hessel 1,2,4 and sediment load of the Yan , X. Mu ff 1,2,3,4 and sediment load changes are a ff This discussion paper is/has been under review for the journal Hydrology and Earth System Sciences (HESS). Please refer to the corresponding final paper in HESS if available. Institute of Soil and Water Conservation, Northwest A&F University, YanglingInstitute 712100, of Soil and Water Conservation, Chinese Academy of SciencesAlterra, and Wageningen UR, P.O. Box 47,University 6700 of AA Chinese Wageningen, Academy The of Netherlands Sciences, Beijing 100049, China the soil and water conservation structures, which is significantly more than the 42 Mt (4) When years were(SPTC) paired and based on used similar toof precipitation assess paired and the years temperature impacts out condition ofiment of human 12 load activities, (50 and %) it 9 showedincreasing was (75 a %) change found decline a with that in decline the 6 runo man in time. sets impacts sediment It relating concentration showed to the Thesignificant LUC complexity other because change of sets and human of show soil impacts. an bothor (5) and the terraces Hu- water and transfer measures the of inthat siltation sloping this about in basin cropland 56 the were Mt into reservoirs of non-food and sediment vegetation behind was check deposited dams. annually Data indicated from 1960–1999 as a result of non-significant decline in precipitation overcrease the in same temperature; period, both andloss. can (3) a help Based very explain on significant a the in- massiment observed curve load, declines analysis 4 with in stages anomalies runo in of(Stage the I), normalized change 1972 runo of to 1986 runo (Stage II), 1987 to 1996 (Stage III) and 1997 to 2010 (Stage IV). Loess Plateau, China,data using of data precipitation and sets temperature,from on and 1952 observed land to data 2010 use on atconservation runo and the structures Ganguyi land and Hydrologic their cover Station. e from Available (LUC), data the monthly on data soil analysis. andthe (1) water The last annual 60 yr runo andof both precipitation had and coe temperature.significant (2) trend Annual of runo linear decline over the period studied. The climate data showed a Runo ties in an integratedknowledge way. Historical of river insight processes, into but also thesement. promote e In more e this study, we looked at runo Abstract Hydrol. Earth Syst. Sci. Discuss.,www.hydrol-earth-syst-sci-discuss.net/10/1213/2013/ 10, 1213–1249, 2013 doi:10.5194/hessd-10-1213-2013 © Author(s) 2013. CC Attribution 3.0 License. Runo River, China: changes over the lastF. Wang 60 yr 1 Shaanxi, China 2 Ministry of water3 Resources, Yangling 712100, Shaanxi, China 4 Received: 6 December 2012 – Accepted: 30Correspondence December to: 2012 F. Wang – ([email protected]) Published: 25 JanuaryPublished 2013 by Copernicus Publications on behalf of the European Geosciences Union. 5 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ff and ff ects on runo as well as sediment ff ff and sediment loss in the ff have been recorded regularly (e.g. 3 − and sediment yield, and causes of signifi- 1216 1215 ff erent kinds of information (written records, Yel- ff for the hilly loess region of the Wuding River Basin, which is one 1 − yr 2 − ectively combat erosion on the Loess Plateau, it is important to have insight ff on the Loess Plateau of over 1000 kgm ects of climate change and human action could not be separated, analysis of ff ff Monitoring of the Yellow River and its tributaries on the Loess Plateau started in the Ren and Zhu (1994) showed how di To e and sediment load. Li et al. (2009) observed a decrease in rainfall and an increase to the relatively limited changesuse in changes land have use during occurred(Feng this et since period; al., 2000 2010; while as Wang muchthat et larger a land al., land result use 2010; Miao changes, ofsoil et i.e. loss the al., on human “Grain 2011). the activity, Other Loess for can2010). Plateau studies Green” And have (e.g. have Peng Hessel significant project indicated et et al. e al., (2010)load 2003; reported Zhang in that et the the main al., reason 2004; Yellowin for Feng River a the et decrease is al., middle in the sediment reachesless, conservation of there are measures the climate that basin trends since have that could the been also 1950’s; implemented explain again the human observed decreases activity. in None runo the load (e.g. Peng etcharge, sediment al., load 2010). and climate Several andvariability authors have and tried have human to recently action quantify the toRiver studied contribution Basin the changes of and observed climate in reported changes. that dis- Lidischarge over et and the sediment al. period yield (2009) 1981–2000 more studied climate than the variability land influenced Hei use change. However, this might be due other hand, Long andHan Xiong Dynasty (1981) (25–220 AD) reported alreadycupied that recorded six very historic tenths high literature sediment ofet from contents: al. the the “the (2010) volume Eastern sediment silt in yield oc- cultivation started one and to barrel deforestation, increase but around of abruptly 3000that water BP were increased sampled”. (1050 maintained further BC) until According around because the to 1000 of 1950’s. Peng AD to levels 1950’s and has shown a gradual decrease over the years in runo low River delta volumes)started indicate around that 1000 the AD.creased Xu serious in (2001) soil frequency found erosion from that the onfrequency bank 10th the depends breaching century Loess of on AD Plateau the onwards. sedimenterosion Yellow According load, on River to in- which the him, breaching Loess apparently Plateau increased following due destruction to of increased the natural vegetation. On the changes in land use. runo Jiang et al., 1981; Zhang et al., 1990; Wan andinto Wang, the 1994). historicalcant development changes. of In runo particular,are it related to is climate importantbuilding or to of to reservoirs. know human Where to activity, humanopportunities e.g. what activity for through reducing is degree land discharge a the use and main soil change main contributing loss and through causes factor, there modified through activity, will for example be source of about 90 %Wan of and all Wang, the 1994). sedimentthe The that entire Loess enters planet. Plateau the Jiang has Yellow18 et River some 000 t al. (Douglas, of km 1989; (1981) the estimated highestof that erosion the erosion rates main rates on Loess may Plateau be tributaries as much of as the Yellow River. Sediment concentrations in 1 Introduction The Yellow River is China’sment suspended second in largest its waters. river, These andsedimentation sediment contents derives in pose its the a major name lower problemters course from because above of the the the sedi- surrounding river1997), landscape has and (Douglas, raised 1989; reservoirs the Zhang are riverChinese et being bed government al., filled to is 1990; with several Zhu sediment committed me- is et (e.g. to Wan being al., combatting and directed these Wang, problems at 1994). and The decreasing much the attention erosion rates on the Loess Plateau, as it is the the e the data indicated that botharea. had a significant impact on runo that is, on average, leaving the Yan River Basin as sediment load each year. Although 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) ), 2 2 and 3 ) and sediment 3 , M m (Ministry of Water Re- 3 1 N) is located in Ganguyi − 0 a 2 42 − ◦ C) were the spatially averaged ◦ and sediment load from 1952 to ) and Baota District (2228 km 2 ff E, 36 (in million m 0 ff , including Jingbian County (256 km erent decades since 1960, and for dif- 48 2 ff ◦ . The basin contains parts of 5 counties, 2 (Wang et al., 2005). 1218 1217 2 and sediment load were 203.5 million m − , respectively; in C (Wang et al., 2010). The study area is covered E) is located in the middle of the Loess Plateau ◦ ff 0 min t 29 , ◦ and sediment yield developments over the last approx- ff max t , –110 0 t ), Ansai County (2699 km 2 38 ◦ N, 108 0 19 and the sediment load module was 7040 tkm ◦ 3 − ) ranges from 2.1 to 4.6 kmkm –37 0 2 21 ◦ The Ganguyi Hydrologic Station (GHS, 109 The climate region of the Yan River Basin is north temperate continental monsoonal, The aims of this paper are (1) to show how discharge and sediment yield from the In this paper we look at runo to the Specifications forrological surface Administration, 2003). meteorological The observation annual of runo China (China Meteo- A 59-yr dataset of2010 precipitation, was analyzed. temperature, Climate runo data werestations obtained of from Yan’an the City 6 county whichPrecipitation level (including is meteorological total located precipitation in ofrain-season the each from middle year May of (a.pptn) and the tominimum precipitation Yan air October River in temperature (r.pptn), the Basin ( in (Fig.data 1). mm) based and on annualthe the mean, Thiessen daily polygon maximum method. records and The of observation and stations data upstream management was area according of GHS (A-GHS) using 41.5 million t, respectively from204 kg 1952–2010. m The average sedimentsources concentration of was China, 2011). 2.2 Data severe throughout the basin anddownstream, causes including enormous in sedimentation the Yellow and Riverdissected high (Hessel due et flood to al., risks long-term 2003). soil The erosionper landform and is km the heavily gully density (the total length of channel Town, Baota County. Its control areaZhidan is 5891 km County (708 km (Fig. 1). The average annual runo County of Yan’an City, Shaanxi Province (Fig. 1). with average annual precipitation varyingtemperature from ranging from 500 8.5 to to 550by 11.4 mm thick and erosion-prone average loess, annual a air type of fine silt soil (Fu and Gulinck, 1994). Soil loss is namely Jingbian County, Zhidan County, Ansai County, Baota District and Yanchang (36 and the area of the whole basin is 7687 km rainfall data and landchanges; use (3) and to cover discuss change implications for data watershed to management. identify causes for the2 observed Materials and methods 2.1 Study area The Yan River is a first-order branch of the Yellow River, China. The Yan River Basin information on land useused are to analyze available the from trendson 1980. and the These changes. the and impact that other climate data and/or sources human are activityYan River has varied had over the last 59 yr; (2) to compare discharge and sediment load with ferent parts of the Yellow River.human These studies action show are that climatic both variability/changedischarge important and and factors sediment to load take onthe into the other is Loess account likely Plateau. to to Which understand depend of trends on these the in factors area outweighs andimately time 60 yr period in that the areRiver. studied. Yan As River, previously one mentioned, of monitoringin the of the rainfall, main Yan discharge Loess River and Basin Plateau sediment started tributaries content in of 1952; the and Yellow satellite images that can be used to derive creasing rainfall and1961–2010. increasing Finally, temperature Miao et on al.found the (2011), a Loess who general increase studied Plateau, in theing over the whole the influence the influence Yellow of River of period human Basin climate activityinfluence and in over from the time climate period – and 2000–2008, even also human outweigh- observed impact varying for degrees di of in temperature over the period 1981–2000, and Wang et al. (2012) also reported de- 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) ff S www. ), sediment load ( R ( ff and sediment sample mea- Soil and Water Conservation ff cult to get, as well as clear descrip- ffi , respectively), runo 1220 1219 min t compiled by the Upper and Middle Yellow River and max t , t ected the detail particularly of the built-up area information. ff : mass curves of anomaly were used to analyze and detect the trends : parametric and non-parametric methods have been developed and ). LUC includes 5 digital maps from 1980, 1985, 1996, 2000 to 2005. The Stage detection Soil and water conservation data up to 1999 came from In the study area, (1) forest means mainly the lands having a tree or shrub-crown The Land Use and Land Cover (LUC) data was obtained from the Data Sharing minimum air temperature ( and sediment concentration (SC).transformed The into anomalies comparable of indices the by mentioned normalized parameters treatment. were The value of Ordinate study, a linear regressionand method sediment is load. used to detect the trends forand precipitation, stages runo as aplotted graph of against the time cumulative characteristic orveloped value for date the on on parameters the annual the Ordinate precipitation (y-axis), Abscissa (a.pptn), (x-axis). annual mean, These maximum mass and curves were de- 2.3 Methods Trend detection successfully applied in hydro-climaticcerning field the analysis detection because of1990; of physical Iorgulescu relationships their and between advantage Beven, ecologicaltailed con- 2004; elements data Xu than (Galeati, other et methods, al.,tions which 2011). of might processes, be However, which they di might require not more be de- developed yet (Walling and Fang, 2003). In this general conditions of the Yan Riversuch Basin, as as man-made well forest, as grass-planting biologicalwith conservation and little measures hillside to closure no (naturalreservoirs, disruption restoration check-dams from area and human key activity), projects for and gully structural control. measures like terraces, Bureau in 2010 based on on-site field surveys and measures. The data covers some Data Compilation of the Yellow River for longer than 3 yr, (3) grasslandand is mixtures predominantly of covered by grass grasses, and grasslike10 plants, shrubs %, (4) or built-up trees, land but comprises withcities, areas the of towns, coverage intensive villages, of use strip covered the byand latter developments structures less along communications including than highways, facilities, and (5)like transportation, wetland/water body swamps, power, areas lakes, include andnewly-built natural check-dams, rivers (6) wetlands and barren land waterlike refers sand engineering to or land structures rocks with where like limited vegetation ability reservoirs cover to is and support normally life less than 5 %. built-up land, wetland/water body and barren land (Liu, 1996). area density (crown closure percentage)chards, of (2) cropland 10 % includes or dry-farming cropland more,agroforestry and as land irrigated well used croplands, as lower-cover mainly nurseries for and food, or- and new cultivated river washland in existence Infrastructure of Earth System Science, Nationalgeodata.cn Scientific Data Shared Platform ( The classification procedure wasinvestigation. based LUC on was classified image into interpretation 6 combined categories with as field forest, arable land, grassland, with water level and flowsurements velocity according of the river national sectionsediment for standards and runo of flow China in on openConstruction channels measurement of (State of China, Quality suspended 1992, Supervision 1993). Bureau and Ministry of map scale in 1985,1 : 1996 250000. and The 2000 seriesscale was of were 1 map used : could to 100000 describefine evaluate and the the information total LUC that and change. change in The over a 1980 time, maps and but with they 2005 larger could was not show very load (in million tons, Mt) data were derived from the daily monitoring records at GHS 5 5 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ff ff (2) (1) (3) (4) cients of ffi erence between ff in 1964 was 4.74 ect from individual and soil moisture, ff ff ff erent years. Therefore if sys- ff and sediment load are precipitation and sediment changes are highly un- ff , sediment concentration and sediment ff ff 1222 1221 ers by less than 1 %; (2) the two years have are the average of the original dataset, original ff m : because the LUC data are only available from o, erences between di and 41.5 Mt, respectively. The di Y ff 3 n − n er by less than 1 %; (3) the two years were more than , and ff o,1 2,3,..., Y 1,2,..., , = = , sediment concentration and sediment load are 0.366, 0.523 m : the areas of each category of the five maps are abstracted by ff i , sediment load and the main weather factors that impact them a, m ff , 177.7 kgm Y 3 , i , 1, a, Y − a,m i , , respectively. Y and sediment load i d, m d, Y and anomaly normalized value, accumulating anomaly normalized values + ff Y i 1 mean 1 , n = erences are found with our approach it indicates that, apart from rainfall and − i X ff m is an anomaly normalized value. When the curve rises or declines, the original /Y i 1 n i o, a,1 mean d, Y a, Y Y = Y Y = = ) derives from equations below: = i i m LUC change analysis The mass curve can show the stages of the whole process and they end at 0 because Similar weather condition analysis o, o,1 o, mean a, Y and is alsoIn the the driving Yan force River for Basin, soil precipitation erosion varies and greatly between sediment seasons delivery and in between this region. 2008 and the sedimentvariation load (CVs) in of 1954 runo and was 0.851, 140 respectively, times meaning that thatstable. the of runo 2008. The coe 3.1.2 Meteorological factors The main weatherand variables temperature. that Precipitation impact is runo the only water source for runo The statistics for runo are shown in Table 1.load The were mean 203.5 Mm annual runo maximum and minimum valuestimes of of each that item in was 2008; large. the The sediment runo concentration in 1966 was 31.14 times of that in based on the LUC maps. 3 Results and discussion 3.1 Statistics 3.1.1 Runo tematic di temperature, other factors are of importance. GIS to show thewas land used use to change illustrate process the of changes several of sections. land A use LUC and change cover matrix for the period 1980 to 2005 events would cause scatter in the di area, because it is wellto known 90 % that of individual yearly rainfall rainfall events totals can (Li contribute et about al., 60 % 2010). However, such an e perature conditions (SPTC) were2008). selected To define to paired periods make withyears the SPTC have analysis the annual following easier rules precipitation were (Wangaverage applied: that et temperatures (1) di al., that the two di 5 yr apart. Because theand natural sediment landform load and changes vegetationUsing evolution in the is a rules quite explained SPTC slow,to above, runo pair 12 emphasize are sets that mainly of this pairedon induced method years just by were assumes human the defined. that activities. yearly It weather averages is and conditions important totals. were This similar is based a significant assumption for the study data in this stage isthe more continuous or change lasts less more than than the 3 average yr, of it the was1980 whole treated and period, as do the respectively. not If same cover stage. and all the years, main and driving because force precipitation of is erosion, the paired main periods source with of similar runo precipitation and tem- Y Y Here, data at year at year 1 and each Y Y ( 5 5 20 15 10 20 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | C ◦ , sed- ff C) was were at ◦ min t and 58.5 Mt, 3 − showed similar , sediment load erence of 3.1 ff and ff before 1988 were t min t C in 1967 and a very ◦ min t C, a di ◦ and ) was very big (2.34). and , 231.3 kgm ff 3 t max t , decreases faster, with a rate of t ff were 230.0 Mm 1224 1223 S were 0.038, 0.019 and 0.046, respectively. The min t C in 1998 and the minimum of 8.4 , SC and ◦ and R max t , t , sediment concentration and sediment load all have significant trends , respectively) all increased significantly during the research period. ff , Stage I), followed by 1972 to 1986 (Stage II), 1987 to 1996 (Stage 0.1) (Fig. 3). The annual mean, maximum and minimum temperatures in 1996. This indicates that mean annual and sediment load , sediment load and sediment concentration in each of these stages was ff min ff ff t P > max t and max t erent years. The mean annual and rain-season precipitation were 504.7 mm and In stage I, the mean a.pptn was 524.9 mm, more than the mean value for the whole Over the whole study period, the mass curves of The river characteristics displayed similar changes, but were much more complex ff , t in Stage III were similar to those of Stage I, but the mean temperature (10.0 (1970 for runo III) and 1997 towas put 2010 in (Stage Stage II IV),value according for respectively to runo (Fig. the rule 2). ofcalculated The stage from detection the abrupt as raw increase a data single and in year. are 1977 The shown mean in Tableperiod 2. (504.7), but the meanriod) annual (Tables 1 temperature and was 2). 9.20respectively, Mean (cooler all than more the than whole the pe- mean values for the whole period. The characteristics time up- and down-phases. than temperature and precipitation (Fig.detect 4). stages According from to the the massand rules curves that sediment of were concentration, applied anomalies 4 to of stages normalized were runo determined. The first from 1951 to 1971 show the change fromplot another could aspect, be e.g. shown(Fig. the 4). as temperature a increasing line in time-value (Fig. 3), butchanges it by is declining a first1988 U-shaped and and curve then in rising;smaller time-mass the than plot changing the points mean forthe of the mean whole of period, whole but process. that The after mass 1988 curve they of were a.pptn higher was than complex with many short- The mass curve oframeter anomaly by comparing values it describes with the theriod. mean change If value the of process that observed of parameter datavalues over a from the will particular given whole be year study pa- positive is pe- and bigger the than mass the curve overall will mean, rise. the The anomaly mass curve of anomaly values 3.3 Stages The annual precipitationsignificant declined ( during the( period of study,The but changing the rates trend of increasing was average not temperature isthan from more higher the maximum temperatures. result of higher minimum temperatures of linear decline inslope of the 1.32, last than sediment 60 yr loadconcentration (0.71), (induced (Fig. and from 2). therefore ratio the The of decreasing sediment rate runo load of sediment to runo 3.2.2 Precipitation and temperature change between the maximum of 11.5 small CV (0.083). The precipitation andiment temperature concentration were and more sediment stable than load. runo 3.2 Trends 3.2.1 Runo The annual runo 436.3 mm, respectively (Table 1),erage for and 86.44 % the of rain-seasonand annual r.pptn precipitation. precipitation (737.6 mm) The accounts in maximum 1964 on recordsand are of r.pptn 3.28 av- a.pptn (195.0 and mm) 3.78 (853.7 mm) in times0.268, the 1997, respectively. minimum and The a.pptn the temperature (259.9 had mm) CV a values mean for value a.pptn of and 9.9 r.pptn are 0.239 and di 5 5 25 15 20 10 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , 3 3 3 all − and and S ff ff C. This ◦ ected by and sedi- ff ff , SC and between Stage R and 97.6 kgm 3 were 145.9 Mm − 3 and 66.7 % for sed- − S ff erences between the ff generation, such as in- ected by multiple factors ff ff in Stage IV was 145.9 Mm ff , SC and R erences between northeastern (decrease), ff 1226 1225 erences in precipitation and temperature between ff or sediment load are usually non-linear because of all , and in Stage II and IV 148.5 kgm 3 ff erent. The mean annual runo − ff cult, e.g. how an increase of just 3.3 % in precipitation and ffi , sediment load and sediment concentration in each stage were ff erences being less than 21 mm (about 5 %). However mean annual ff erent from the trends for the whole of China (Piao et al., 2010), which, for and 226.6 kgm ff and 16.5 Mt, respectively, all less than the mean values for the whole pe- , sediment load and sediment concentration, the di 3 ff − 3 − erent stages is di ff , 2.04% for sediment concentration and 6.11% for sediment load). The mean ff erent stages were very di erences in the mean annual value of each parameter are quite small (2.28% for Changes in runo In the 4 stages (Table 2), the mean annual precipitations of Stages I, II and III are very For runo In Stage I and III, the mass curves are, on the whole positive, meaning that the ff ff tions (SPTC) allows better study of the changes because the same premise is set with ment generation. Due toconcentration, the sediment strong concentration correlation would betweentween also sediment precipitation load be and and reduced. runo the sediment The processes relationships that be- operateterception by between vegetation precipitation and and litteret on al., runo 2005), the as soil well as surfacelike infiltration (Helvey and weather, and evaporation landform which Patric, and are 1965; a soil Huang sediment and load vegetation between conditions. paired A years comparison with of similar runo precipitation and temperature condi- determines the transportation andvoirs siltation of downstream sediment (Terrio, in 2008; therelationships river Maren with channel et pptn. and reser- Thisother al. factors suggests 2009; than that Ma precipitation, thishave like et a parameter temperature significant al., and is negative 2012), relationship human likelyhigher with activity. has more temperatures temperature. This no can a is induce good perhaps increased because evaporation the and reduced runo other than climatic ones mightLUC also change be and of constructions importance. in the Thus, Basin the should impacts also3.4 of be factors considered like and Relationship analyzed. between river and meteorologicalThe factors relationships between riversediment and load climate and factors are annualever shown and sediment in rain-season concentration, which Table precipitation 3. is are a Runo all meaningful indicator very for significant. river quality How- because it found to bethrough much consideration of greater only than thethe di changes di in precipitation.5.1 % Trying in temperature to could accountiment induce load an for (Stage increase III of this compared 17.3 % to for Stage runo II). These data, therefore, suggest that factors similar with the di precipitation in Stage IVthe was temperature 57.48 increased mm in lessis each than stage similar Stage from to III 9.02, the (aboutMinistry to of increasing 9.52, 11 %). Water 10.01 temperature Resources Meanwhile, and and trendbut Ministry 11.06 is for of very Environmental the di Protection whole ofthe China, Yellow 2010), period River 1960–2006, Basin showed (The northwestern strong (increase) di and southeastern China (increase). annual values are usually moredi than the mean annualruno value for the whole period.annual values The in Stage II and IV are less than their long-term mean annual values. riod, the decreases being 28.3 %, 45.1 % and 60.2 %,di respectively. just 63.4 % oftimes that of in that Stage in I.231.3 kgm Stage The IV. sediment The load meanrespectively. in The sediment reduction Stage concentrations from I in Stage wasIV I Stage and 58.48 to Mt, I I Stage (about about and IV 58%). 3.5 III was were 133.7 kgm in Stage II werewas less nearly than the those same464.0 mm, for as about the the 8 whole % wholewas period, less period 1.2 than except mean. degrees that for higher The97.6 for precipitation than kgm mean the which the a.pptn whole whole in period, period. Stage and Mean IV the mean was temperature higher than Stage I and the mean for the whole period. All the mean characteristics 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | er- ff ects ff having positive S and means the value of the R S and sediment load in the river. all increasing (positive direction), ff S and decreasing direction in SC and , SC and R R 1228 1227 , SC and R reduced (directions negative for all three param- erence for ff S erent. When comparing the later year with the earlier ff between paired years in Table 4 is from 0.02 %–0.97 % t , SC and R and sediment load when investigated through SPTC analysis are very di ff erent kinds of land use categories in 1980 and 2005 (Table 5). S ff and sediment load between paired years with SPTC ff , SC and erence of a.pptn and R ff and SC can be attributed primarily to human activity. From the data it appears 0.87 %–0.56 % of the relative value of paired years, respectively, but the di S , − R Because of the very dissected landform in this region, all categories of land are A matrix based on the LUC change for three counties was developed to show the Since precipitation and temperature were very similar for the paired years, the e The di , and 1 set (1) with SC having negative direction but both land, and 14 497 ha of arable land and 4105 ha of grassland changed into forest. In distributed as small fragmentized piecesand its (Fig. branches 5). had The no clear arableparts change, land of but along Zhidan in the the County, Jingbian higher Yanand River area, county patches mainly and the of Ansai west forest county, and arable and north(indicated land grassland by use in a decreased, that dark region purple expanded color and in even the joined map together transfer for 2005). between di This shows that 1.28 ha and 12.89 ha of forest changed into grassland and built-up was converted from arable land.body The (Fig. actual 6) area was changedue less in area than to of 500 ha new wetland in andof arable the water check-dam land study building formation period, across but250 in the ha. this gullies. the is The upstream a area decrease parts of of barren of 28 land % reservoirs remained and stable because at forest increased continuously fromin 44.91 2005, thousand a ha conversion inas of 1980 arable 3.13 % to land of 63.50 declined2005, the thousand from whole but ha 270.78 region not thousand to continuouslyThe ha forest as grassland in in area it 25 1980 decreased yr. increasedha from to The by 274.82 in 254.29 area 2.17 thousand 2005, used thousand thousand ha almost hanearly in ha all in doubled 1980 from of because to 1985 of 272.38 whichis to thousand the occurred still 1996. intensive from less houses than 1996 and 2 to infrastructure thousand 2000. ha. development, The but More built-up than land half area of the area converted to built-up area Figure 5 provides a visual representationof of the GHS LUC in for 1980 4 counties andForest, in 2010, the arable and area upstream land Fig. 6 andmore provides than grassland details of 99.20 are % the the LUC of for main the the whole land same period. area. use Over categories the accounting period for studied, the area covered by 3.6 LUC change on that in theimpacts middle on and soil later and waterthe years loss other of than hand, in the the theto 1980’s, early impact have human 1950s of been and activity human positive 1960sin had when activities (set 1991 compared more in 1, and 2 with the 2007 negative and the were 1970smore 3). positive 1960s negative and On when in (set early compared 1993 4–9). with 1980s compared The 1978 to appear and human 1981. 1998, impacts respectively, but year in each setyears of that paired showed years, that thereeters), are and 6 3 sets sets (4,2 5, (2, sets 6, 3 (7 8, and andS 10 11) 9) and with with 12) a ofdirection. increasing 12 direction paired in are shown in Tablelater 4. year A is less positive than di is that considered of the an earlierbecause improvement year the of in goal the of the two the paired mainmore integrated management years. water practices land Such and in a sediment surface this decrease on semi-arid condition site, region or is of to to the retain reduce runoand basin ences in slow enough to neglect over intervals of several decades. 3.5 Runo The changes in runo just one additional assumption, that the evolution of natural landform and vegetation is 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , ). 3 of 3 and sed- ff ected by engi- , sediment load ff ff of sediment accumu- 3 and erosion (Wang et al., ff and soil erosion by 80 % to 100 % ff ects of changes in climate, changes ff for the sediment (Ran et al., 2004), this 3 1230 1229 , sediment load and sediment concentration. − ff when considering the 40 yr period between the and erosion. Furthermore, Sect. 3.7 showed that and sediment load 1 . There was also 18.8 Mm ff − ff 2 and sediment load of the Yan River was a ff ect of conservation engineering. ff . The siltation amount measured in these reservoirs was 105 Mm 2 ) in strong storms even though the canopy coverage is high (Wang 1 Soil and Water Conservation Data Compilation of the Yellow River Basin − a Soil and Water Conservation Data Compilation of the Yellow River Basin 2 − of which was silted in the Wangyao Reservoir (in Ansai County), built in 1970 3 Thus, it is clear that runo Areas covered by man-made forest and grassland were quite large by 1999, with Using a dry bulk density of 1.35 tm There were 22.45, 2.87 and 3.98 thousand ha of terraces, check-dam land and irri- According to neering measures, land use change and climatic change. However, the data that have iment load that can bedata observed from showed the a available relatively data smalland for the decrease very Yan in River significant Basin. rainfall, These a decreasesData definite in on increase runo land in use temperature, catchment change consisted indicated of that anboth the increase of main which in changes would forested that influencesoil area have runo and water and occurred conservation a in engineeringiments the decrease measures that also in could trapped otherwise arable large have amounts land, partly of reached sed- the outlet of the Yan River Basin. 10 000 tkm and Liu, 2000). 3.8 Causes for decreased runo Earlier sections of this paper presented evidence regarding changes in runo 57.53, 41.58, 24.63 and 15.51respectively thousand ( ha of arbor, shrub,The economic trees soil and and grass, waterof control vegetation, and functions the ofwell controlled soil these (Jiao erosion areas et al., of arelike 2000). apple land closely Although in orchards, with related this includes coverage toloss region keeping more cultivation from coverage the of than evaporation economic land by 70 trees, % between wild trees would grass, bare be the to soil avoid erosion moisture rate could be very high (8000– sion erosion (Fang etyield al., because 1998), of its it fertile alsoincreased soil production has and potential more a available allows 4 water local (Xuon to people et the to 10 al., remote reduce 2004). times cultivation and This higher, and2003). sloping resulting harvesting and land more that is stable, more prone to runo sediment from the upstream area and provides a new local base level to reduce inci- gation cropland by 1999. Terraces cancompared reduce with runo sloping cropland (Zhan and Yu, 1994). Check-dam land not only retains amounts to 2265 Mtenter of the sediment Yan that River,start or was of 56.62 silted Mt implementation yr in andof this 1999. 41.50 region This Mt and is per a(Table therefore year 1) much did and that greater is not is value evenmean) as than transported and high the from as III mean the or (54.91 value Mt higherbecause Yan mean) most than River of the (Table Basin 3). the values In measures as found were for fact sediment constructed stages the load less I amount than (58.48 per Mt 40 yr year ago. is much greater area of 896.4 km 96 Mm with an upstream arealated in of the 820 km 43sedimentation key behind projects check dams. for gully control built since the 1980’s, and 1555 Mm In addition to climate variation/changesthe and previous land sections, use engineering change, is also whichand likely were to sediment presented have concentration in influenced of runo theon Yan River. the This impact section of discusses soil the andmade available water to data conservation integrate the engineering, evidence and presented inin for Sect. the land 3.8 e use, an and attempt the is e (Table 6), there are 2 reservoirs in the upstream area of GHS with a total controlled wetland and water body, respectively.1980 The and increase 2005. in built-up land was fast3.7 between Soil and water conservation engineering the same period, 2715 ha, 474 ha and 46 ha of arable land changed into grassland and 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | and and and ff ff ff , sediment ff erent scales show that signif- ff cult to distinguish the impacts induced ffi 1232 1231 and sediment load, this also indicates that other ff and sediment load would change solely under the ff ect of human action from that of climate. In this study, we and sediment load change were detected. Especially, the and sediment load are not likely to be linear. However, the , sediment load and climate change could be divided ac- ff ff ff ff cult to say, as the trapped sediment might also have deposited and sediment load. and sediment load. Therefore, it can be expected that further ffi being 17–38 % higher than in neighboring stages, and sediment ff , sediment load and sediment concentration are larger than in- ff ff ff , sediment load and sediment concentration of the Yan River and other ff and sediment load in Stage III (1987 to 1996) did not match the whole change and sediment load declined dramatically over the last 60 yr. The non-significant ff ff The stages of river runo Hence, there are indications from the comparison of climatic data with runo The SPTC analysis of paired similar weather years shows that for years with sim- The LUC change data show an increase in forested land, and a decreaseData on in sedimentation arable at engineering structures of di Decreases in runo load being 66–70 % higher. decline in precipitation andthese significant changes increase in in runo temperature can only partly explain cording to mass curve ofized anomalies characteristics of could observed data, put andsis. all the 4 change mass clear processes curves in stages ofruno one of normal- plot runo easily for betterprocesses, with analy- runo functions and processes. Inecosystems addition and human process. activity hasby It climate also can change undoubtedly be and influenced developing human very management activities, di yet and this adaptationruno information strategies. can In be the of Yan great River value Basin, for the river has decreased runo human intervention by wayinfluence of runo land managementrivers measures on the would Chinese be Loess able Plateau. to further 4 Summary and conclusions Global climate change has undoubtedly already influenced ecosystems and their otherwise, while conversely newwater sediment that might flowed out have of, been e.g. the entrained reservoirs. by thesediment clearer load that suggestsediment changes, that and there factors is also besides evidence climate that human were activity (structures, involved land in use) runo would be is however di icant amounts of sediment were captured. What the impact of this at catchment scale ilar rainfall and temperature,concentration the and later sediment load chronologicalcaution for year that 6, had needs 9 be lower andvidual made runo 8 events about on out this yearly of method totalsfactors 12 because of yr, than runo of respectively. climate the Despite also large the play influence a of role. indi- land, which according to acceptedsediment knowledge load would at result catchment in scale. a decrease of runo ature and rainfall and runo relatively low correlation between sedimenttemperature (Table concentration 3) and does precipitation indicate as thatother factors sediment well than concentration as climate. is partly controlled by veloped that describes howinfluence runo of climate change. By extrapolatingthen this able equation to to separate other decades, thedid they e not were use suchdata, an such assumption, as: but rather looked at indications thatcreases are in found temperature in and the factors decreases than in temperature rainfall. and This, rainfall are in also itself, at is play, as not relationships proof between that temper- other these factors because all these factorspartly are in operating simultaneously dependence and on perhapscan each even other. only The be data quantifiedassumption do if provide made significant some by indications, assumptions Miaoneglected but are et these and made, al. that such (2011) for as that the for human 1950’s example influence data the in a the regression 1950’s equation could could be therefore be de- been used in this paper do not provide proof about the relative importance of each of 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , 1965. forecasting, ect of both ff ff relationships: an ff and sediment load, ff 10.1002/ldr.3400010206 , 1994. , 1990. ect of check-dam to intersect sediment 10.1029/WR001i002p00193 ff , 2010. and sediment loss. 1234 1233 10.1002/ldr.3400050105 ff and sediment would therefore be due to human , 2003. ff and sediment load. However, as the e , 2005. 10.1080/02626669009492406 ff ective cover rate of woodland and grassland for soil and water , 2004. ff and soil loss at the scale of the whole basin. erences in runo ff ff in the last 60 yr. This is one of the clearest indications that human The research described in this paper was conducted within the framework cult if not impossible. Nevertheless, the results of this study clearly 1 − ffi 10.1016/j.geomorph.2010.01.004 10.1029/2004WR003094 10.1016/S0341-8162(03)00070-5 10.1016/j.jhydrol.2004.08.036 China, Land Degrad. Dev., 5, 33–40, doi: Soil Conservation: Problems and461–479, Prospects, 1981. edited by: Morgan, R. P. C., Wiley, Chichester, conservation, Acta Phytoecol. Sin., 24, 608–612, 2000 (in Chinese). Hydrolog. Sci. J., 35, 79–94, doi: United States, Water Resour. Res., 1, 193–206, doi: in the middle reach of Yellow River, J. Hydraul. Engin.,land-use 20, change 49–53, 1998 in (in hilly239–248, Chinese). doi: catchments of the Chinese Loess Plateau, Geomorphology, 118, ulations of land usedoi: scenarios for a small Loess Plateau catchment,and Catena, 54, canopy 289–302, rainfalldoi: interception using the strainalternative gauge approach method, todoi: data J. analysis Hydrol., and 311, modeling?, 1–7, Water Resour. Res., 40, W08403, China: review and assessment, Land Degrad Dev., 1, 141–151, doi: Beijing, China Meteorol. Press, 35–44, 60–67, 93–116, 2003 (in Chinese). 1989. Thus, both climate change and human activity are important factors in explaining The paired-year method can be useful to study the impacts of human activities, as The human impacts relating to LUC change and soil and water measures in this Jiao, J., Wang, W., and Li, J.: E Fu, B. and Gulinck, H.: Land evaluation in an area of severe erosion:Helvey, J. the D. and Loess Patric, J. 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Elsen of The for his comments and Ms. Demie Moore for improving the observed variationare in integrated runo at catchment scale,observed accurate changes determination were of exactlyis due which extremely to part di of climate the change, and which to human management basin were very importantfood both vegetation or because cultivable of terraces, and thecheck because transfer dams. of of siltation Data in sloping for reservoirsannual cropland and the average behind into study of non- sediment sitelarger were show than silted that the in about amount thewas 2264.96 of basin Mt 41.50 sediment during Mtyr in that 1960–1999. total is, Thisactivity or on value had 56.62 average, a is Mt leaving significant impact the on Yan Basin, runo which it can be assumedsuch that other as factors natural that landformcompared cause change, changes to vegetation in the and runo activitieslected, soil of observed evaluation di human are beings. slowaction. 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Res., 42, 20–29, doi: value M m Statistic MeanMinimum(Year)Maximum(Year) 106.0 203.5Standard 502.1 1.3deviation 41.5 (2008)Confidence (2008) 182.0 177.7levels 12.3 (1964) (2008) 74.47 (95.0 %) 383.0CV 504.7 (1964) (1997) 19.41 35.23 259.9 853.7 (1966) (1997) 436.3 93.00 9.18 195.0 (1964) (1967) 737.6 120.65 (1964) 9.9 (1954) 24.24 8.4 116.94 11.5 (1998) (1952) 31.44 17.4 0.366 (1999) 0.82 15.6 19 30.47 (2006) 0.851 0.84 4.2 0.21 2.2 0.523 5.9 0.93 0.239 0.22 0.268 0.24 0.083 0.048 0.222 Table 1. ature of the Yan River in 1952–2010. Zhang, J., Huang, W., and Shi, M.: Huanghe (YellowZhang, River) Q., Fu, and B., Chen, its L., Zhao, estuary: W., Yang, Q., sediment Liu, ori- G., and Gulinck, H.: Dynamics and driving Xu, J.: Historical bank-breachings of the lowerXu, Yellow X., River Zhang, as H., influenced and Zhang, by O.: drainage Development of basin Zhan, check-dam S. systems and in Yu, gullies Y.: on Methods the of Loess Calculating e Zhu, T., Cai Q., and Zeng, B.: Runo Xu, H., Bin, Z., and Song, Y.: Impacts of climate change on headstream runo 5 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1 ∗∗∗ SC 0.904 t C ◦ R ∗∗∗ ∗∗∗ 3.8 3.6 0.779 mm 57.511.0 1.1 60.9 10.5 11.6 1.9 20.3 20.2 0.3 − − − − − − 1 ∗∗ min t 3 , sediment concentration and − ff 0.181 1 0.210 0.938 SC a.pptn 0.336 − − 56.9 57.8 82.8 35.8 − 133.8 129.0 − − − − − − ∗ 1 ∗∗ ∗∗∗ ∗∗∗ max Mt kg m 70.0 42.0 71.9 38.4 25.6 43.7 0.316 0.395 − − − − − − 0.471 0.515 − − − 3 RS t t 1240 1239 ∗∗ ∗∗ ∗∗ ∗∗∗ ∗∗∗ 38.0 84.2 36.6 89.4 29.4 12.8 M m − − − − − − 0.377 0.399 0.356 0.762 − − − % % % 17.3 66.7 52.6 3.3 5.1 % cient of significance at 0.001, 0.01 and 0.1 is 0.418, 0.333 and 0.216, ffi 1 Value Value 34.6Value 22.0 78.1 16.7 0.5 Value ∗∗ ∗∗ ∗∗∗ cients between precipitation, runo 0.151 1 ffi 0.406 0.358 − 0.542 − ∗∗ ∗∗∗ ∗∗∗ ∗∗∗ 0.182 0.030 0.046 0.911 a.pptn r.pptn 59, the correlation coe 0.359 erence (IV–I) erence (III–II) erence (IV–III) erence (II–I) − 0.436 0.537 = III (1987–1996)IV (1997–2010) 235.3 54.9 145.9 226.6 521.4 16.5 10.0 97.6 464.0 11.1 I (1952–1971)II (1972–1986) 230.0 200.6 58.5 32.9 231.3 148.5 524.9 504.7 9.2 9.5 ff ff ff ff − n Di Di Di Stage Di , sediment load and sediment concentration. ff Linear related coe Mean characteristics of each stage as identified by mass curve anomalies of normal- max min a.pptnr.pptnt 0.974 t 1 t R SCS 0.154 0.162 Note: When respectively. sediment load of Yan River in 1952–2010. Table 3. Table 2. ized runo Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ), = . 2,4 2.05 3.63 1.09 0.04 0.67 0.35 2.57 j V 11.12 − − − − − − − and − 6= 800.67 S i 1592.71 means 3,2 and 44 911.34 V j 3.4 0.11 , 270 777.18 274 820.79 i denote: 1 37.1 1.09 52.4 2.1 28.5 2.38 − V 2,3 − − − j V − − , 6.2 51.3 2,1 and in 2005 if 0.78 4.25 13.1 0.37 0.5 24.6 55.6 4.210.69 13.3 4.6 − V 10.48 76.3 12.42 23.1 i − − − − − − j 251.85 251.85 − − Direction Mt Dir SC 3 − − − − − − − Barren land. 83.0 3.32 150.2 4.42 117.4 9.78 = − ∗ kg m − − # erence 6.6 111.8 Dir ff 2.67 155.1 6.57 220.0 2.73 51.0 1.43 9.0 − 16.74 123.0 − − − − − ), but there were about 14.5, 2.7, 0.5 3 2,2 3.5 0.25 5.2 68.1 2.13 24.9 88.6 2.61 28.7 1.44 84.1 26.4 2.2 V − of 2005. The elements 137.7 5.51 − − − − − 20.04 1091.28 j 800.67 ) 1980 t R j 0.87 0.51 0.80 0.26 138 0.27 0.50 18.6 − − − − − − in 1980 changed into category − i 1.28 12.89 0.05 0.58 0.26 83.7 0.03 0.54 0.66 59.4 Wetland and water body; 6 − − − − a.pptn = 5 9 32 0.02 34 0.97 25 0.21 2521 0.38 0.00 66.8 1214 0.20 0.52 0.00 0.56 32.7 20 1312 0.35 0.63 0.00 − − − − − − − − − − − − Year 1242 1241 erence of year, and shows the synchronicity of the − ff of 1980 and column S Mt % % M m i land land water body land 481.40 3 − SC Built-up land; 5 kg m , and area of category = j −− − − − − − − − 3 R = i 1 Forest 2 Arable 3 Grassland 4 Built-up 5 Wetland and 6 Barren Amount ) divided by the di and sediment load within paired similar precipitation years. S ff Year Grassland; 4 S Mt M m (SC or = R 3 − SC is the value at the cross of row j , kg m i V 3 R erence of ff M m Arable land; 3 LUC Change matrix of upstream area of GHS from 1980 to 2005 (in ha). Changes of runo erence is the time and characteristics value of Year 1 minus that of Year 2. ff = 1 Forest 44 897.17 2 Arable land 14 496.59 253 045.70 2714.55 474.47 45.88 5 Wetland and water body 6 Barren land Di Year ∗ ). Year LUC2005 Amount 63 498.61 254 291.35 272 380.42 2005 ( 1595.16 1137.16 251.85 593 154.55 1980 3 Grassland 4104.85 764.26 269 664.58 287.10 (i) 4 Built-up land No. Year 1 of paired years Year 2 of paired years Di 1 1952 133.9 124.0 16.6 1984 202.0 99.1 20.0 2 1955 119.7 65.8 7.9 1989 208.3 216.0 45.0 3 1963 192.3 182.0 34.9 1988 330.0 265.0 87.3 4 1958 287.8 253.0 72.9 1983 221.0 97.9 21.6 5 1959 282.0 322.0 91.0 1980 144.0 102.0 14.7 6 1960 163.4 199.0 32.4 1972 130.7 148.0 19.3 7 1962 158.6 98.8 15.7 1976 162.1 93.6 15.2 8 1966 277.6 383.0 106.0 1971 193.9 260.0 50.4 9 1963 192.3 182.0 34.9 1983 221.0 97.9 21.6 1011 1978 1981 212.0 197.0 167.0 85.6 35.2 1991 16.9 193.4 1993 158.0 223.4 30.6 203.0 45.4 12 1998 186.4 149.0 27.8 2007 127.0 37.2 4.7 Dir (Direction) is just to show the changing direction of a certain set of paired years (increase or decrease). It was 5.2 Note: The value Table 5. Forest; 2 Note: Table 4. # the ratio of di characteristics and time. A negativea value positive means value the means value the decreased value over increased the over years the which years are which desirable, are and undesirable. the area with no change in category if and meanwhile about 764 ha of grassland and 481 ha of wetland and water body changed into arable land ( thousand ha of arable land in 1980 converted into forest, grassland and built-up land, respectively ( e.g. there were about 270.8about thousand 253 ha thousand and ha 254.3 of thousand land ha was arable always land arable in land 1980 without and any 2005, change respectively ( V and Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 43 3.0 38.0 18.8 25.4 896.4 217.8 104.5 141.0 − − − − − − − − − −

ina) 1.17.3 1.9 11.5 96.0 8.5 15.0 22.9 820.0203.0 76.4 14.8 275.2 1219.5378.5 59.8 1239.5 1554.5 59.8 1677.8 County District County 1244 1243 2 3 3 2 3 3 3 3 Mt 129.5 11.5 Mt 9.9 15.5 Mt 371.5 1646.4Mt 510.9 80.7 1673.4 2098.6 80.7 2265.0 Yanchang Yanchang

anCity ’ Baota Baota Control Area km CapacitySiltation M m M m Siltation M m Siltation M m Yan An’sai An’sai Location of the study area (the Yan River Basin, Ch Basin, River (the Yan area the study of Location Fig. 1. Zhidan Jingbian Jingbian for gullycontrol Control Area Capacity km M m Check dam Number Set 688 3049 149 3886 TypeReservoir Character Number Unit Ansai SetKey projects Baota Number Zhidan 1 Amount Set 1 17Amount of 26 siltation M m Engineering measures of upstream area of GHS before 1999 (in ha). Location of study area (the Yan River Basin). Fig. 1. Table 6. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

Year

= = 0.046x =0.019x = = -0.869x P>0.1 P<0.01 = 0.038x = 0.038x - 87.801 P<0.001 - 20.816 + 2225.6 + P<0.001 - 65.743 t tmin R² = = R² 0.7396, tmax Y R² = 0.1542, 0.1542, = R² R² = = R² 0.0153, Y R² 0.6393, =

a.pptn Y

Y ℃ in tmin and tmax t, S fitLinearof S = 0.12, sig.=0.007 = -0.7105x -0.7105x = 1449 + 20.0 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 2 S Y R Year load change in 1952-2010 in change load SC SC fit Linear of -2010 t tmin fit t of Linear fit tmin of Linear = -2.3434x = 4820 + = 0.1873, = sig.<0.001 2 1246 1245 SC Y R R fitLinearof R a.pptn tmax Linear fit a.pptn of Linear fit tmax of = -1.321x= 2820.3 + = 0.0928, sig.=0.019 , sediment concentration and sediment load change in 1952–2010. 2 S ff Y R 1951 1956 1961 1966 1971 1976 1981 1986 1991 1996 2001 2006 0.0 1951 1956 1961 1966 1971 1976 1981 1986 1991 1996 2001 2006 80.0

480.0 400.0 320.0 240.0 160.0

Annual precipitation and temperature change in 1952 in change temperature and precipitation Annual 0.0

concentration (SC) in kg/m in (SC) concentration , Sediment load (S) in M t M in (S) load Sediment , sediment and concentration sediment runoff, Annual

3 900.0 800.0 700.0 600.0 500.0 400.0 300.0 200.0 100.0

, Sediment Sediment , m M in (R) Runoff of Values a.pptn in mm in a.pptn 3 Fig. 3. Annual precipitation and temperature change in 1952–2010. Annual runo Fig. 2. Fig. 3. Fig. 2. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

GHS ics of GHS in 1952-2010 1952-2010 in GHS ics of

1248 1247

GHS LUC of the Yan River Basin from 1980 and 2005 and 1980 from River Basin the Yan of LUC Mass curves of anomalies of normalized characterist normalized of anomalies Mass curves of Fig. 5. Mass curves of anomalies of normalized characteristics of GHS in 1952–2010. (The LUC of Yan River Basin from 1980 and 2005. Fig. 4. (The boxes in the figure are the change points) points) change the are the in figure boxes (The

Fig. 5. Fig. 4. boxes in the figure are the change points). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

land Barren 2005 Barren land Barren body Wetland and water and water body water 2000

land Built-up 2.80 2.10 1.40 0.70 0.00 3.50 1996 1249 1985 LUC type 1980 Forest land Arable Grassland Built-up land and Wetland 0.0

50.0 LUC change in the Yan River Basin from 1980 to 2005 1980 from River Basin Yan the in change LUC

300.0 250.0 200.0 150.0 100.0 Area in 1000 ha 1000 in Area LUC change in the Yan River Basin from 1980 to 2005. Fig. 6.

Fig. 6.