Hidrológiai Közlöny, 2021 (101. évfolyam)
2021 / Különszám
113 Vörösmarty Charles J., Green Pamela A., Fekete Balázs M.: A metrics-based approach mapping precursors of water conflict 2018); NASA Global Land Data Assimilation System (Rodell et al. 2004), have transformed assessments of water resources from the relative static, national-scale mapping as recently as the 1990s (Shiklomanov and Rodda 2003) into a dynamic vision of a rapidly evolving resource. In the context of producing bio-geophysical precursors we are now better equipped to produce metrics with potential relevancy in predicting the precursors of water stress and hence conflict. On the human dimensions side, analysis of environmental conflicts and societal responses (i.e., cooperation, conflict, forced migration) have also been an arena of advancing study (Diehl and Gleditsch 2018, Abel et al. 2019, OSU 2020, Pacific Institute 2020) and new technical approaches are being considered, including the use of artificial intelligence to incorporate these factors into a forecasting capability (Kuzma et al. 2020). We see value in using existing databases and frameworks to uncover basic patterns of water system stress using a metrics-based mapping approach, which is organized around the topology of river networks and drainage basins that uncover possible upstream-downstream contrasts and asymmetries. We produce a set of spatial hypotheses for where stresses on the water system are likely to arise. If these hypotheses are proven to be correct, the pressures can motivate human decisions on how best to alleviate these baseline water resource stresses. It will then be up to human institutions and actors to execute responses to the baseline stresses, optimally taking a route toward cooperation or relocation as opposed to new or continued hostile actions. The many papers in this special issue are a testament to the numerous perceptions and responses humans will adopt in response to water security threats. While our approach can help to point out some of the key factors that underpin these human actions, we in no way claim a capacity to formally predict the onset of water conflicts per se. We instead are searching for their precursors, which ultimately merit further testing and empirical validation. TECHNICAL APPROACH Mapping of various stressors on water systems and environment has well established practice in the scientific literature. More recently, Vörösmarty et al. (2010) proposed a comprehensive framework to evaluate combined effects of these stresses and express the overall states of the water resources and the supporting ecosystems with a single composite metric. The threats on water resources largely coincide with the stresses that lead to water related conflicts, therefore the methodology described in Vörösmarty et al. (2010) appears to be well suited for the development of a new metrics-based approach to map potential hotspots and larger regions for potential conflicts. Even if we incorporated all the available information affecting water resources and the environment, our analysis still would not to be exhaustive (Kuzma et al. 2020). We understand that the sources of conflict are complex and interdisciplinary—involving several interacting natural and human factors that operate over different time and space scales (from local to mega-regions, from single extreme events to decadal trends) (Diehl and Gleditsch 2018). They are not a simple function of water availability, but instead determined by interactions among societal, cultural, historical and ethnic factors that drive water policies and management. Nonetheless, geophysical realities dictate and to varying degrees motivate human action in response to these challenges. Conflict precursors and choice of mapped drivers While the factors to spark water conflicts could be nearly limitless, we identify some essential candidates. These are assembled as geospatial maps depicting four main Conflict Precursors (CPs): (i) composite river/surface water threats, (ii) climate variability stress index, (iii) transboundary complexity, and (iv) fragile states index. The first two are biogeophysical in character and the last two represent human dimension factors. Biogeophysical inputs These refer to a broad array of factors that are determined primarily by the environment. While there are detailed and purely biogeophysical descriptors of the hydrologic cycle describing its state and dynamics for use in Earth system studies of the hydrosphere, we instead need to formulate a water resources perspective. Thus, while we employ water balance hydrology, digital river networks, and river dynamics modelling, we quantitatively convert these into a composite metric capturing the state of the freshwater resource base and its availability for human use. Our estimates require information on the condition of the natural capital and ecosystem services that generate water resources. We also track water supplies on a journey from their upstream watershed origins to the ocean, tabulating the number of people served downstream as the resource is delivered to lower parts of each drainage basin. The resource base and its beneficiary populations are reduced whenever water becomes scarce in physical terms or degraded through pollution to a level where its use is impaired or requires rehabilitation. The state of the water resource system can be expressed by a composite river/surface water threat index, determined by the presence or absence of stress agents. We consider 23 individual stressors contributing to a single, composite threat scoring. These stressors are organized into four major categories of human-environment interactions: (i) watershed disturbance; (ii) pollution; (iii) water use management; and (iv) biotic factors that apply pressure to aquatic ecosystems. The biogeophysical state of the resource is thus determined by a broad cross-section of human-environment interactions. Examples include: the stewardship (or lack thereof) of upland source water landscapes; diffuse and point sources of sediment and nutrient pollution from agriculture, cities, or mining; the depletion of river corridor flows by irrigation or over-engineering of river basins; and, introduction of aquatic invasive species. Water resources are thus defined by their interactions with geological, biological, and human-based management systems. Given growing concerns regarding a possible intensification of climate change induced variability of hydrological variables that could give rise to more significant droughts or flooding (COHS 2011, USGCRP 2017) we have included an additional climate variability stress index, calculated as the coefficient of variation for simulated
