Jianfeng Zhang Forestry Measures for Ecologically Controlling Non-point Source Pollution in Taihu Lake Watershed, China Forestry Measures for Ecologically Controlling Non-point Source Pollution in Taihu Lake Watershed, China Jianfeng Zhang Forestry Measures for Ecologically Controlling Non-point Source Pollution in Taihu Lake Watershed, China 123 Jianfeng Zhang Institute of Subtropical Forestry ChineseAcademy of Forestry Hangzhou China ISBN978-981-10-1849-7 ISBN978-981-10-1850-3 (eBook) DOI 10.1007/978-981-10-1850-3 LibraryofCongressControlNumber:2016945114 ©SpringerScience+BusinessMediaSingapore2016 Thisworkissubjecttocopyright.AllrightsarereservedbythePublisher,whetherthewholeorpart of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission orinformationstorageandretrieval,electronicadaptation,computersoftware,orbysimilarordissimilar methodologynowknownorhereafterdeveloped. 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Preface Taihu Lake basin is located in the core area of the Yangtze River Delta; the total area of the basin is 36.9 thousand km2 of which the water area of Taihu is 2338 km2,coveringJiangsu,Zhejiang,andAnhuiprovincesandShanghaicity.Owingto favorableclimate andnaturalconditions, this regionwas developed very early and is playing an important role in socioeconomic development of China. In 2005, the GDP(grossdomesticproduct)ofthebasinarea accountedfor about11.7 %ofthe whole country. With a rapid development of economy and society in Taihu Lake basin, the water consumption and wastewater discharge are increasing, and the water quality of the basin is declining since past 30 years. During 2005, the water quality of the lakebasinalongthewatershedof2700kmlongwasstudiedandfoundthatforover 89 % of the basin, the annual water quality deterioration was of class III standard, and 61 % was worse than the class V standard. The average water quality com- prehensive evaluation of Taihu Lake was for the inferior class V (including TP − (total phosphorus), TN (total nitrogen) index), whereas the NH -N index was for 3 theclassII,TPwasforclassIV,TNindexwasinferiortotheclassV,andCOD MN (chemical oxygen demand) was for class III. Among various factors of water pollution and eutrophication in Taihu Lake basin,thecontributionofnon-pointsourcepollutioniscrucial.Thestatisticsofthe Taihu basin showed that the contribution of non-point source pollution to the drainage was around 347,000 tons of COD and 2.5 million tons of NH -N. 3 According to an estimate of the former State Environmental Protection Administration, the water pollutants in the country from the industries, human living,andagriculturalnon-pointsourcepollutionwereapproximately1/3each.Of thepollutionloadinTaihuLake,83 %ofTNand84 %ofTPwerefromfarmlands, rural livestock and poultry breeding industry, urban and rural combination areas, and rural life. The contribution of non-point source pollution was far more than point source from industries and urban life. In the plain area of Taihu Lake basin, addition of COD to the rivers was 346.9 thousand tons per year with the largest proportionfromruralhumanliving,accountingfor41.6 %ofthetotalCODinthe v vi Preface river,followedbyaquacultureproduction,accountingfor27.2 %ofthetotalCOD. The addition of TP to the rivers was 6.7 thousand tons per year with the largest proportion from rural life, accounting for 50.6 % of the total TP, followed by farmland runoff pollution, accountingfor 26.9 %. The additionofTN to the rivers was 64.8 thousand tons per year with the biggest share from rural human living, accounting for 32.8 % of the total, followed by livestock and poultry breeding, accounting for 23.9 %. In specific, addition of NH -N to the rivers was 25.1 3 thousand tons per year with the largest proportion from rural life, accounting for 60.2 % of the total, followed by farmland runoff pollution, which accounted for 26.7 %ofthetotal.Thus,therearevarioussourcesforpollutionofriversandlakes, i.e.,TNandNH -Narethelargestpollutantsinruralareas,rurallife,andfarmland 3 runoff,whileTPismoreinrurallifeandlivestockandpoultryfarming.Thereby,it isnotdifficulttounderstandwhyin2007blue-greenalgaebrokeoutinTaihuLake. In order to overcome the serious non-point source pollution in Taihu Lake watershed, the following measures are generally taken: (1) Ecological ridge technology:Runoffisanimportantwayofnutrientloss.Thecurrentfarmlandridge is only about 20 cm high in the farming area of Taihu Lake basin which can produce surface runoff easily at the time of higher rainfall. It is estimated that by heightening the existing ridge by 10–15 cm, the runofffrom 30 to 50 mm rainfall can be effectively prevented and can reduce most of the farmland runoff. At the same time, some plants can be planted on both sides of the ridge to form a buffer zone,whichcaneffectivelychecksurfacerunoffandtherebyreducenutrientlosses through runoff water. (2) Ecological ditch technology: Currently, most of the ditchesarewithhardcementsurfacewhichresultsinthedischargeofsurfacerunoff directly into rivers causing eutrophication of water. Therefore, it is wise to change the existing channels to hardened eco-channels by hard boards with holes which makethecropsorgrassestogrowandabsorbnutrientsfromtheleachingwater.By this way, the loss offarmland nutrients can be effectively intercepted. At the same time,certainplantscanbeplantedatthecenteroftheditches,whichcanreducethe velocityofwaterflow,increasetheretentiontime,improvecropnutrition,andalso improve self-purification capacity of water bodies. (3) Ecological wetland treat- ment technology: Through the construction of ecological ditches and ecological interception system, most of the nutrients lost from farmlands can be intercepted, but still some nutrients go into the river. Man can take advantage of the existing ecological wetlands or artificial floating islands by planting emergent plants, leaf floatingplants,etc.,tofullyabsorbandutilizethesenutrients.Thehydraulicplants havingsomeeconomicvaluecanbeselectedtoensurecertaineconomicbenefitsto local farmers besides improving water quality. Forestry measures play a certain role in controlling non-point source pollution and protecting water security. In order to understand the role offorestry measures on water quality improvement, some projects have been undertaken since 2008 whicharesupportedbyStateMinistryofScienceandTechnologyandDepartment ofScience and TechnologyofJiangsuProvince.Thisbookhasbeenwrittenbased on the research findings of the projects. Preface vii This book mainly focuses on ecological approaches of preventing and control- ling non-point source (NPS) pollution based on forestry measures. Firstly, the characteristics ofNPSpollutioninTaihuLakewatershedandwater eutrophication evaluation methods are described. Then, the role of relevant forestry measures in combating water pollution such as public welfare forest development, urban for- estry development, techniques of hedgerows planting in slope lands, shelter belt establishment, N and P absorption by willows, hydrophyte selection, and land use pattern optimization is presented. Correspondingly, quantified data on the effect of forestry measures on soil properties, plant species diversity and source reduction and sink increase of NPS pollution are given in this book. Moreover, for the first time, the landscape change and its effect on water quality in Taihu Lake are dis- cussed, in addition to purification of eutrophicated water and dynamic kinetics of nitrogen absorption by trees. Finally, the techniques of development of riparian forestbuffersandponds–wetlandsintegratedmanagementsystemareindicatedand described. This book is useful for researchers, lecturers, professionals, and administrators working on water environment and ecological development as well as graduate students, senior undergraduates, and persons interested in water security. Hongzhou, China Jianfeng Zhang April 2016 Acknowledgements I take this opportunity to express my gratitude to the persons who have been instrumental in the successful completion of this book. Thesuccessofanyprojectdependslargelyontheencouragementandguidance of many colleagues apart from the efforts of oneself. The present work is no way different from this and is accomplished very much by teamwork. The colleagues from the Institute of Subtropical Forestry, Chinese Academy of Forestry, Dr. Guangcai Chen, Dr. Qihua Shan (now working at Yixing city Department of Agriculture and Forestry), Prof. Jingmin Jiang, Dr. Huasen Xu, Prof. Mukui Yu, Prof. Yangdong Wang, Prof. Jiyuan Li, Prof. Fubin Tang, Prof. Xiaoping Gu, Dr.XuezhiFang,Dr.TongguiWu,Dr.MingWu,Dr.XiaoshengYang,Dr.Sheng Li,andDr.HonggangSun,andmystudents,YingWang,QingbingWang,ZeboLi, LiWang,HaoWu,HuiSun,YongqingLiu,QuanquanYang,YiniCao,ZeyuCai, andXiaogangLi,allhelpedinvariouswaysintheresearchworkoftheproject.My friendsProf.JinchiZhang(NanjingForestryUniversity),Prof.XiufenLi(Shanghai AcademyofAgriculture),Mrs.ChunxiaPan(ForestryDepartmentofAnjiCounty), Prof. Bo Jiang (Zhejiang Academy of Forestry), and Prof. Dr. Zheke Zhong (Hangzhou Bamboo Research and Development Center of State Forestry Administration) also contributed immensely in the project work. Altogether, they are a great inspiration to me in working hard to complete the project. I am very grateful to all of them for their motivation, valuable and constructive suggestions, and encouragement during research work as well as in writing this book. I am highly grateful to all my teachers, colleagues, friends, and organizations (the Zhejiang Key Scientific and Technological Innovation Team of Forestry Ecology) for their help and constant encouragement throughout the project work. I extend my thanks to Dr. T.B. Basavaraju (professor and head of Horticulture Research Station, Arsikere, Karnataka, India) for reviewing few chapters of the manuscriptandlanguagepolishing.IamalsothankfultoDr.XiaoliPeiofSpringer Asia for her kind help in the preparation of the manuscript. I am very much grateful to my parents for their affection, encouragement, endurance, sacrifice, and love bestowed upon me throughout the project work. ix x Acknowledgements I express my deep sense of gratitude and affection to my wife, Mrs. Junqing Cao, and 17-years-old son Kai Zhang for their endless love, sensible cooperation, and encouragement throughout the project work and in the preparation of the manuscript. Hongzhou, China Jianfeng Zhang April 2016 Contents 1 Characteristics of Non-point Source (NPS) Pollution in Taihu Lake Watershed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Analysis on Source and Sink of Agricultural Non-point Pollution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2.1 Framework of Source and Sink of NPS Pollution. . . . . 5 1.2.2 Components of the Source . . . . . . . . . . . . . . . . . . . . 6 1.2.3 Distribution of the Sink . . . . . . . . . . . . . . . . . . . . . . 7 1.3 Formation of Non-point Source Pollution . . . . . . . . . . . . . . . . 8 1.3.1 Rainfall. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.3.2 Human Activity. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.4 Management and Prevention of NPS Pollution. . . . . . . . . . . . . 10 1.4.1 Key Measures on NPS Pollution Control . . . . . . . . . . 10 1.4.2 Reduction on Pollutants Diffusion . . . . . . . . . . . . . . . 11 1.4.3 Strengthening of Pollution Monitoring . . . . . . . . . . . . 12 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2 Evaluation of Water Eutrophication on Taihu Lake-Connected Channels in Yixing City. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.2 Materials and Methods. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 2.2.1 Study Area Description. . . . . . . . . . . . . . . . . . . . . . . 19 2.2.2 Determination of Parameters . . . . . . . . . . . . . . . . . . . 21 2.2.3 Computation Carlson Trophic State Index. . . . . . . . . . 23 2.3 Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.3.1 TN, TP, and Chlorophyll a (Chla) . . . . . . . . . . . . . . . 23 2.3.2 Carlson Trophic State Index . . . . . . . . . . . . . . . . . . . 25 2.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 xi