Groundwater mapping and locally engaged water governance in a small island terrain: Case study of Karainagar island, Northern Sri Lanka

Groundwater is a vital resource under threat in island communities. Karainagar, 22 km2 island, one of seven islands off the coast Jaffna Northern Sri Lanka, with its population just about 11,000 persons, experiences seasonal water shortage, and salinity groundwater as twin threats impacting on their lives. This paper reports 3-year study (October 2019 to September 2022) map dynamics Karainagar spatially seasonally discusses patterns revealed terms community needs, policy implications, governance ideas that could already be considered by relevant authorities citizens jointly. Thirty-six dug wells used for drinking, domestic, agricultural, public purposes were selected, level, salinity, pH changes recorded along daily rainfall. offers thorough description geography, land use, distribution wells, bodies, followed discussion current status island. Year-to-year differences rainfall pattern resulted different rates change range level corresponding reverse seen some exceptions across Cumulative required reach full capacity ranged from 652 892 mm over 3 years an average figure 739 rain. implies any further during early phase main rainy season potential surface storage runoff. Practices such unregulated pumping construction tube are argued contributing increase levels health implications residents. A participatory approach overcomes limitations existing institutional proposed. Its success based broad stakeholder engagement, improved equity, transparency when supported adequate policies village aquifer monitoring will enable sustainability resources Karainagar. 岛屿社区的地下水是一项面临威胁的重要资源。卡莱纳格尔岛 (Karainagar)占地22平方公里, 是斯里兰卡北部贾夫纳海岸外的七个岛屿之一, 人口仅约11,000人, 季节性缺水和地下水盐度是影响其生活的双重威胁。本文报告了一项为期3年(2019年10月至2022年9月)的研究, 从空间和季节方面测绘了卡莱纳格尔岛的地下水动态, 并探讨了在社区需求方面揭示的模式、政策影响、以及一系列治理理念, 这些理念已经可以由相关部门和公民共同衡量。选择了36口用于饮用、家庭、农业和公共用途的挖井 (dug well), 并记录了水位、盐度、pH值变化以及每日降雨量。本文详尽描述了地理、土地利用、水井和水体的分布, 随后探讨了该岛的地下水现状。降雨模式的逐年差异导致不同的水位变化率和范围, 盐度也出现相应的相反模式, 个别情况除外。三年来, 达到水井满容量所需的累计降雨量为652至892毫米, 平均降雨量为739毫米。这意味着在主要雨季的早期阶段, 多余的降水都是可导致储存或径流的潜在地表水。不受监管的抽水和建造管井等做法被认为会促进盐度水平升高, 进而对居民健康产生影响。提出了一项克服现有制度方法局限性的参与式治理方法。这项方法的成功加上广泛的利益攸关方参与、改善的公平性和透明度、以及充足的政策支持与村级含水层监测, 将为该岛地下水资源的可持续发展创造适宜条件。 El agua subterránea es un recurso amenazado en las comunidades insulares. Karainagar; una isla de siete islas frente la costa el norte con población aproximadamente personas, experimenta escasez estacional y salinidad como amenazas gemelas que afectan sus vidas. Este documento informa sobre estudio años (octubre septiembre para mapear dinámica aguas subterráneas espacial estacionalmente, analiza los patrones revelados términos necesidades comunitarias, implicaciones políticas e gobernanza ya podrían considerarse. por autoridades competentes ciudadanos conjuntamente. Se seleccionaron 36 pozos excavados beber, domésticos, agrícolas públicos, se registraron cambios nivel del agua, junto precipitación diaria. ofrece descripción detallada geografía, uso tierra, distribución cuerpos seguida discusión estado actual isla. Las diferencias año otro patrón lluvia dieron resultado diferentes tasas cambio rango inverso correspondiente observado algunas excepciones toda La acumulada necesaria alcanzar plena capacidad osciló entre durante tres años, cifra media lluvia. Esto implica cualquier adicional fase inicial temporada lluvias principal superficial potencial almacenamiento escorrentía. argumenta prácticas bombeo no regulado construcción entubados contribuyen al aumento niveles salud residentes. propone enfoque participativa supera limitaciones institucional existente. Su éxito, basado amplia participación partes interesadas, mejora equidad transparencia, cuando está respaldado adecuadas monitoreo acuíferos aldea, permitirá sostenibilidad recursos As consequence rise, economic growth, technological advance worldwide, wide use has risen factor 6 past century, whereby availability likely throughout year due climate phenomena (UN-Water, 2020). shrinking world overexploitation through unsustainable abstraction at exceeding recharge precipitation (Asoka et al., 2017; Graaf 2019; Shah 2001; Sikka 2021). In general, withdrawal source, ground source (aquifer) or tidal either permanently temporarily, municipal (direct population), agricultural (irrigation, livestock, aquaculture), industrial (FAO, 2023). countries, order protect both sources environment, withdrawals ground, surface, regulated system licenses (DEFRA, Rameshwaran 2022; Santato 2016). communities, it often primary drinking water, irrigation, supply. However, unique geological hydrological characteristics landscapes can make managing complex task (Vlahović & Munda, 2012). The small very around like sand cays Caribbean Sea coral atolls Pacific Indian Oceans characterized does not exist exploitable form, fresh limited. addition, over-extraction pollution lead scarcity degradation quality, which have severe consequences On these islands, conventional options freshwater supplies limited development rainwater (UNESCO, 1991). Province (NP) including Peninsula adjoining perennial rivers, climatic conditions many parts there favorable storage. Therefore, demand critical matter peninsula (Thushyanthy Silva, 2012) islands. Inhabitants entirely dependent all needs. Due extensive movement people war rapid urbanization process now underway, traditional knowledge security conservation being eroded. Technological developments social contribute contamination extraneous sources. Ancient forms conservation, particularly variety bodies capture rainwater, been existence ranging size, sophistication, serving multiple needs community, recharging water. These had maintained ages functional ways, almost collective action until 1970s. Such tanks ponds areas well sacred temple state decades neglect filled purposes. Mikunthan al. (2013) commented same phenomenon how large number varying sizes present mainland past, function holding high proportion resources, dwindled 2000 recent decades, those belong temples. Small usually thin lenses aquifers highly vulnerable pressure external factors effects, frequent storms, increasing anthropogenic pressures excessive (Singh Gupta, 1999; Wu 2022). Hence, specific management practices, assessment development, need studied separately larger “freshwater lens” layer effectively floating above denser saline normally found coastal settings (Bedekar Underwood 1992; Werner 2013, 2017). Freshwater display dynamic spatial variability temporal fluctuations volume. combined effects geology, variability, impact weather events, influences, within heterogeneous remain area research address concerns Aquifer engagement key element ensure sustainable terrain (Masood measuring, monitoring, analyzing physical, chemical, biological aquifer. It plays essential role understanding detecting problems, contamination, saltwater intrusion, over-extraction. Regular also help crucial landscapes. Furthermore, impacts exacerbate environmental stresses (Abobatta, rise heavy storm surge intensify compound flood risks future low-lying (IPCC, Sebastian, risk posed sea intrusion into considerable deltas (Lall 2020; Lassiter, 2021; UN, 2013). depends several type, amount withdrawal, geologic structure (Chang 2011; Luo issues ecological Thus, hydrogeology hydrology develop rational program management, but intent going beyond more descriptive studies attempted other while approaching here perspective incorporates technical, social, economic, policy, political dimensions plans (Maheshwari 2014). took inspiration Australian funded MARVI project (Managing Recharge Sustaining Use Village-level Intervention) operation time Rajasthan Gujarat States India (www.marvi.org.in; Maheshwari, Maheshwari Incorporation this work graduate larger, province-wide “Water Security Participatory Action Research” (WASPAR) place 2020. maps spatiotemporal goes discuss what human usage. salinization discussed next, we close taking up pathways available steps taken towards our study. arranged five sections: introduction (Section 1) geography elements methodology 2). results mapping three given Section 3. 4 four outlined earlier, 5 concluding remarks. angles investigation portion aspects relevance achieving locally engaged identified discussion. part covering 2020–2021 only presented National Conference Water Supply Drainage Board (NWSDB) Lanka held December 14–16, 2022 (Karthiga area, known Karaitivu (tivu = island), islets located sides rectangular bounded Palk Strait fourth facing lagoon causeway linking (Figure 1). covers inland measures km North–South East–West. generally flat 2a) much below m measured mean (MSL). total 10,678 persons 3,618 families live nine administrative divisions (Statistical-Handbook, 2022), approximately half peak late 1980s. outside NP property farming strong sense belonging community. notable size original immigrated overseas. Agriculture fisheries major income residents, supplemented trade extent foreign remittances. soil related limestone geology land. Lagoonal estuarine deposits unconsolidated brown gray common type Much farmland growing (Maha) rainfed paddy cultivation field crops. Unlike rest NP, vegetable subsidiary crop undertaken dry Yala months low poor quality Figure 2b shows 2,697 scattered (Saravanan 2013), translates density 123 per km2. masks higher domestic tree covered residential (over 200 km2) than cropped (20 km2), primarily rice irrigated agriculture. comparable significant practices reported 15 (Sood Smakhtin, 2015). cover composed native tropical trees, Palmyra palms, thorny bushes. Households rely washing comes few moved bowsers/tankers. withdrawn most show Electrical Conductivity (EC) EC commonly measure saltiness addition ~2,700 23 ponds, numerous smaller designed livestock purpose 2013; Statistical-Handbook, among mapped villagers reliable 3a–h examples indigenous waterbodies exclusion schemes Close 99% kiṇaṟu 3a), 2 8 depth, diameter 1 Although mainly constructed exploit provide round, season. Almost lined without kerb protection. Maintenance done households, agro-wells middle lands government Agrarian Service Centre. times, drilled kuḻāy become preferred 3b). kuḷam Tamil 3c) silted lack maintenance, tuṟavu 3d) disappeared silting. hand, kerṉi 3e) regularly local groups. Wetland taravai 3f) body wetland ecosystem serves commons grazing. Saltwater times locations named Saambalodai Bund, Vernon Kiluvanai vaaikaal outlet, Periya mathavady vaaikaal, Sakkalavodai Thillai Paravaikkadal (Provincial-Statistical-Information, Two these, Bund kept Irrigation Department. intended prevention retention influence 3g,h). above, tracts open wetlands capable providing pastures inundated, carrying zone bushes vegetation directly enrichment ecosystem. (NWSDB), Jaffna, implemented piped supply scheme except residents supplement About 117 get benefitted 225 m3 monthly (District-Statistical-Hand-Book, 4a). helped improve access good household use. household's bowsers/tankers 4b), where abstracted mainland. 150 m3. falls country region Lanka. Rainfall distinctly follows bimodal noted regions Heavy obtained Northeast (NE) monsoon season, nominally August December. April July Southeast (SE) monsoon. Annual since 2012 Centre, lowest recording 517 (in calendar 2016) highest 1868 readings whole lower annual 5a). Piratheeparajah (2015) variations 1972 2014 days decrease indicating intensity events increased. Manawadu Fernando (2008) although reduced, declined. temperature October February period March wet seasons, 21.5°C 33.2°C 2021 5b). evaporation expected follow 1,314 data Meteorological Department 2019–21(Figure 5c). K1 K36 inventoried. enabled respective physicochemical parameters: first pilot commenced November 2019, 20 included (Anojan 2020), 16 added 2020 representative all. initial chosen leaders phase. Later 2020, was decided entire systematically study, grid cells developed, accommodated additional randomly fall gaps. eight private currently areas. All assessed weekly Owners (17) group provided measuring equipment notebooks coached own wells. Sampling analysis carried out staff who contact owners regular basis. (15) participated two consultative workshops, presentation interim findings time. (kerb height bottom level) using meter tape. Positioning hydraulic heads respect MSL then determined Global System (GPS) surveys. measurements made Multi parameter (Model: Hach HQ40D) Chemistry, University Jaffna. Daily record Services defined 12 beginning ending following (e.g., 1, 2021, 30, 2022, 2021–2022). coincides onset Maha rains and, therefore, cropping rainfall, pH, comprising 2019–2022 paper. Qualitative owner consultations ongoing course. 6a (mm day−1) variation 2019–2022. 6b,c portrays (m) (mS cm−1) sampled period. sliced sections shown 2a examination clusters each section rather examine together. 7a sections. Well elevation marked range. 7b according mark acceptable (2,500 μS cm−1 2.5 mS indicated horizontal line. maximum minimum 7c, points years. cumulative year. recognized today, circles 7b. EC, (K20, K30, K32, K34) selected (i.e., data) 9a–c, line represents continue generate kind fulfill modeling so far below, authorities. Salinity permanent feature lived experience communities livelihood agriculture, employment, demographics. rising (Pathmaja course island's nearness benefits connected via 1900s. dramatic numbers 2b) inhabited 1990, complete evacuation 1990s war, partial return gradually years, electrical pumps technology new dimension presence remarkable preponderance unacceptable puzzling landscape. Anecdotal evidence having declined extraction Wells K3, K20, K32 category drinkable acknowledged us 9b). relationship 6a–c. clearly indicate year-to-year days, rain length seasons. Differences observed 2020–2021, minor corresponds SW (Yala) period, 20-year If occurs April–May would exists An abnormal certain K10 K16) 6c) raises question because too lying ground. aspect choice investigation. When comparing 2019–2020 appears drier is, K13 K31, dried after NE rain, 2021–2022 wetter differed 7a). Most K9 K16, reached slightly surface. expressed nearer expect behave similarly fact showing changes, example, K15 K32. Similarly, values, K5 K18 7b). observations somewhat unexpected raise interesting questions. At time, figures hold maintenance abandoned long K11 K17). 7c Some location-specific observation