1 / 28

Espen Ronneberg, UNDESA

Allen L. Zack, Hydrologic Consultant for UNDESA. EFFICIENT WATER-SUPPLY DEVELOPMENT AND MANAGEMENT FOR SMALL, ARID, OCEANIC ISLANDS BASED ON WATER USE. Espen Ronneberg, UNDESA. towards the sustainable development of water and the reduction of waste.

tamyra
Download Presentation

Espen Ronneberg, UNDESA

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Allen L. Zack, Hydrologic Consultant for UNDESA EFFICIENT WATER-SUPPLY DEVELOPMENT AND MANAGEMENT FOR SMALL, ARID, OCEANIC ISLANDS BASED ON WATER USE Espen Ronneberg, UNDESA towards the sustainable development of water and the reduction of waste

  2. Many SIDS have inadequate freshwater supplies, yet lack the financial and technical resources to implement seawater desalination for all of their population.Non-potable water uses have been sought for brackish and gray wastewater to moderate the demand for potable water.The sustainable development of water and the reduction of wastewater in SIDS can be improved by matching appropriate water-quality requisites to the various water-use sectors in order to accommodate both potable and non-potable water supplies.

  3. There can be no single strategy for appropriate water-quality partitioning based on use.The amount of saltwater (chloride concentration) – or other contaminants – present in the water supply would dictate which non-potable use of the water can be considered.Existing and evolving technologies can be considered to provide adequate, affordable, and sustainable water for all sectors with minimal environmental disturbance.

  4. Water-quality requisites for intended use

  5. Wastewater discharge to the environment is reduced by optimizing freshwater production and matching water quality to other water uses

  6. Islands of the Caribbean Region

  7. The availability of freshwater resources depends upon the geomorphologic history of the islands and rainfall accumulation Greatest availability: large islands, sufficiently elevated to have orographic effects and exhibiting extensive coastal accumulation of sediment St. Lucia Lowest availability: small, low-lying islands having less than 50 centimeters of yearly rainfall, without coastal embayments Middle Caicos, TCI

  8. Fresh groundwater lenses subject to vertical saltwater intrusion (upconing) during well pumping. Small, arid, limestone/coralline platforms or atolls extending a few meters above sealevel, exhibiting subterranean drainage Case study I

  9. Freshwater lens typical of small, low-lying carbonate islands showing disruption of the freshwater/saltwater interface by pumping wells Minimal, unsustainable freshwater recovery using trench-and-skimming, radial wells, gentle/intermittent abstraction

  10. SCAVENGER-WELL COUPLES • Only hydraulic formula for stabilizing the interface • Greater quantities of fresh groundwater continuously • Scavenger-well effluent must be discharged to the sea or deep wells – or used for some non-potable water use

  11. Hydraulic maintenance of the freshwater lens by operating the scavenger well Production well withdrawing a mix of freshwater and saltwater Scavenger well withdrawing saltwater Production well withdrawing freshwater Pre-pumping conditions

  12. PROVIDENCIALES, TURKS AND CAICOS ISLANDS The Bight, freshwater lens

  13. Improvement in freshwater abstraction by pumping the scavenger well scavenger well as production well is pumped scavenger well pumping alone production well pumping alone detectability limit (500 mg/L cl) USEPA limit (250 mg/L cl) production well as scavenger well is pumped Time (decimal days from beginning of pumping)

  14. COZUMEL, QUINTANA ROO MEXICO Cozumel wellfield

  15. Simultaneous pumping of production and scavenger wells for pozo 4, eje 6+200

  16. Majuro Atoll, Republic of the Marshall Islands

  17. Efficient utilization of scavenger-well effluent: flushing toilets washing vehicles filling swimming pools Final wastewater discharge: the sea deep wells, screened far below the freshwater/saltwater interface

  18. Elevated islands of relatively small size, having high rainfall, intermittent surface drainage and sedimentary coastal embayments Intermittent streamflow recharges the wedge of fresh groundwater residing in coastal sediment. During droughts, saltwater migrates inland horizontally from the sea, displacing abstracted or naturally discharged freshwater. Case study II Tortola, BVI

  19. Fresh groundwater withdrawals from coastal embayment aquifers can initiate the horizontal migration of saltwater toward pumping centers. Retention structures placed at appropriate downstream locations in ephemeral drainages enhance groundwater recharge by retaining rainfall runoff for greater periods of time.Although retention structures have been used throughout history to increase groundwater storage, no engineering studies have been conducted to relate storage to aquifer diffusivity, rainfall, basin evapotranspiration, and surface-water head.

  20. However, wastewater issues are somewhat more problematic in islands having retention structures because there are fewer options for environmentally compatible discharge. Wastewater will be of higher quality in the elevated islands having coastal retention structures because of its origin; it can often be considered for agricultural or golf-course irrigation.

  21. Annual rainfall accumulation for Caribbean islands with the longest period of record

  22. Islands without freshwater resources Desalination: • Flash distillization • Efficient reverse osmosis • (Clark pump) Catchments: • Rooftop • Roadway • Runway

  23. International forum of hydrologic scientists in cooperation with AOSISDemonstrating, documenting, and publicizing new technologiesSmall Island Developing States Information Network (SIDSNet) Application of new technologies to improve freshwater development and reduce wastewater

  24. Support provided by: U.N. Development Program University of the West Indies Center for Environment and Development U.N. Department of Economic and Social Affairs U.S. National Weather Service, National Oceanic and Atmospheric Administration Programa de Modernización del manejo del agua (Mexico), U.N. World Meteorological Organization

More Related