Land Use, Climate, and Water Resources—Global Stages of Interaction
Total Page：16
File Type：pdf, Size：1020Kb
water Editorial Land Use, Climate, and Water Resources—Global Stages of Interaction Sujay S. Kaushal 1,*, Arthur J. Gold 2 ID and Paul M. Mayer 3 1 Department of Geology & Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20740, USA 2 Department of Natural Resources Science, University of Rhode Island, Kingston, RI 02881, USA; [email protected] 3 National Health and Environmental Effects Research Lab, Western Ecology Division, US Environmental Protection Agency, 200 SW 35th Street, Corvallis, OR 97333, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-301-405-7048 Received: 13 September 2017; Accepted: 19 October 2017; Published: 24 October 2017 Abstract: Land use and climate change can accelerate the depletion of freshwater resources that support humans and ecosystem services on a global scale. Here, we briefly review studies from around the world, and highlight those in this special issue. We identify stages that characterize increasing interaction between land use and climate change. During the first stage, hydrologic modifications and the built environment amplify overland flow via processes associated with runoff-dominated ecosystems (e.g., soil compaction, impervious surface cover, drainage, and channelization). During the second stage, changes in water storage impact the capacity of ecosystems to buffer extremes in water quantity and quality (e.g., either losses in snowpack, wetlands, and groundwater recharge or gains in water and nutrient storage behind dams in reservoirs). During the third stage, extremes in water quantity and quality contribute to losses in ecosystem services and water security (e.g., clean drinking water, flood mitigation, and habitat availability). During the final stage, management and restoration strategies attempt to regain lost ecosystem structure, function, and services but need to adapt to climate change. By anticipating the increasing interaction between land use and climate change, intervention points can be identified, and management strategies can be adjusted to improve outcomes for realistic expectations. Overall, global water security cannot be adequately restored without considering an increasing interaction between land use and climate change across progressive stages and our ever-increasing human domination of the water cycle from degradation to ecosystem restoration. Keywords: land use; climate; urbanization; agriculture; dams; stream burial; urban evolution; salinization; Anthropocene; stream restoration; best management practices; models 1. The Emerging Global Water Crisis Over 75% of Earth’s land surface has now been impacted by human development [1], which exerts an expanding footprint on water resources. There are distinct patterns in the evolution of land use change [2,3], and land use is a template on which climate interacts to influence the quantity and quality of Earth’s water [4]. In order to support human-dominated land use, ground water in semi-arid and arid landscapes has been decreasing by approximately 150 cubic km per year due to increasing extraction [5] (and references there in). Water stored as ice on land, which is critical for major drinking water supplies, has decreased at a rate of approximately 300 cubic km per year due to warming and changes in regional precipitation patterns [5] (and references there in). In fact, access to clean water is considered one of the contemporary grand challenges for engineering by the U.S. National Academy of Engineering (http://www.engineeringchallenges.org/challenges/water.aspx). Globally, Water 2017, 9, 815; doi:10.3390/w9100815 www.mdpi.com/journal/water Water 2017, 9, 815 2 of 10 Water 2017, 9, 815 2 of 10 majorGlobally, impacts major are impacts being caused are being by thecaused increasing by the irrigation increasing and irrigation accompanying and accompanying dam construction dam andconstruction groundwater and groundwater extraction [6]. extrac Thus,tion a water [6]. Thus, crisis a has water been crisis proposed has been as proposed a major global as a major issue global [7,8], andissue much [7,8], work andhas much described work impairmentshas described and impairments alterations ofand water alterations systems of [9 ,10water]. However, systems critical [9,10]. questionsHowever, remain critical regarding questions ourremain current regarding state of our the current world’s state water of and the howworld’s water water impairments and how water have evolvedimpairments over timehave [evolved11]. Can over we altertime our[11]. future Can we course alter toour avoid future a globalcourse water to avoid crisis a global and related water pitfallscrisis and [7]? related How will pitfalls we manage [7]? How water will in we the manage future [ 12water,13]. Thein the papers future in [12,13]. this special The issuepapers on in Land this Use,special Climate, issue on and Land Water Use, Resources Climate, provide and Water practical Resources information provide and, practical along withinformation case studies and, fromalong differentwith case regions studies of from the world,different help regions address of somethe worl of thed, help most address important some water of the management most important questions water facingmanagement us now. questions facing us now. 2.2. HumanHuman DominationDomination ofof Water-fromWater-from Degradation Degradation to to Restoration Restoration Cycles Cycles HumansHumans have have dominated dominated Earth’s Earth’s ecosystems ecosystems over millenniaover millennia [14]. Since [14]. recordedSince recorded history, humanshistory, havehumans influenced have influenced every major every hydrologic major hydrologic process of process the water of the cycle water including: cycle including: altered rainfall altered regimes rainfall (e.g.,regimes modified (e.g., bymodified urban areas), by urban accelerated areas), runoff accelerated and overland runoff flowand fromoverland impervious flow from surfaces impervious and tile drains,surfaces reduced and tile infiltration drains, reduced from soil infiltration compaction from and soil impervious compaction surfaces and impervious [15], and induced surfaces changes [15], and in evapotranspirationinduced changes in from evapotranspiration irrigated agriculture from and irrigate treesd inagriculture urban areas. and Recharge trees in urban has also areas. changed Recharge due tohas consumptive also changed processes due to consumptive in ground water, processes and there in gr isound also water, less recharge and there due is to also melting less recharge snowpacks due andto melting shifts in snowpacks regional rainfall and shifts patterns in regional [16]. Water rainfall systems patterns also [16]. evolve Water over systems time due also to adaptationsevolve over intime response due to to selectiveadaptations pressures in response and decisions to select byive humans pressures [2,3]. Furthermore,and decisions there by arehumans coinciding [2,3]. changesFurthermore, in aquatic there ecosystem are coinciding structure, changes function, in aqua andtic associated ecosystem services, structure, coupled function, with vulnerability and associated to climateservices, at coupled each step with of human vulnerability domination to climate of the waterat each cycle step from of human degradation domination to restoration of the water (Figure cycle1). Itfrom is now degradation well known to that restoration human activities(Figure have1). It contributedis now well to known increasing that emissions human ofactivities greenhouse have gases,contributed which to is responsibleincreasing emissions for regional of greenhouse climate change gases, and which variability—this is responsible can for spur regional regional climate and localchange adaptation and variability—this and mitigation can strategiesspur regional [17, 18and]. local However, adaptation restoration and mitigation efforts to strategies regain losses [17,18]. in structure,However, function, restoration and efforts services to regain are unrealistic losses in unlessstructure, they function, consider and the pathservices of degradation are unrealistic of waterunless systemsthey consider (Figure the1). Thus,path of restoration degradation and of water water management systems (Figure are “ex 1). post Thus, facto” restoration responses and with water an “impairmanagement and then are repair”“ex post approach facto” responses [11]. Instead, with wean need“impair a predictive and then andrepair” proactive approach approach [11]. Instead, based onwe an need understanding a predictive ofand both proactive root causes approach and trends based ofon water an understanding degradation andof both an appreciation root causes and for nonstationaritytrends of water and degradation uncertainty and in climatean appreciation trends—e.g., for nonstationarity historical trends and in theuncertainty past do not in alwaysclimate helptrends—e.g., us predict historical future changes trends inin waterthe past management do not always [12]. Overall,help us thepredict losses future in structure, changes function,in water andmanagement services due [12]. to Overall, land use the change losses have in structure, contributed function, to a global and services water crisis due relatedto land touse the change resiliency have andcontributed resistance to of a global water towater climate crisis change. related to the resiliency and resistance of water to climate change. Figure 1. Conceptual model describing how land use and climate change alter the amount and quality Figure 1. Conceptual