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A platform for research: civil engineering, architecture and urbanism
Importance of Leaving Intermittent Rivers and Ephemeral Streams (Ires) Untouched in a Sustainably Built Environment
Intermittent rivers and ephemeral streams (IRES) are temporary waterways that flow only at certain periods of the year and consist of more than half of the world’s total stream/river length. They have essential hydro-ecological functions and provide many ecosystem services but are widely ignored and considered as mere surface flow or trenches, and Sri Lanka is no exception. That is why we do not see such streams even in semi-urban townships, an indication that those have been either reclaimed or replaced with man-made (e.g., concrete-lined) drainages. In this study, we discuss the importance and sustainable management of IRES in the dry and intermediate climatic zone of Sri Lanka which has townships, extensive agriculture, tourism infrastructure, and where the built environment shows signs of expansion. A unique characteristic observed in IRES of the study area was their signature high infiltration at the stream bed (about 40 times that of the catchment), and somewhat high infiltrations in the low-flow areas. High infiltration of the beds contributes to groundwater recharge, where all rainfall received during the dry season (including runoff from the catchment) is infiltrated (therefore, no flow in the stream). To control flooding in the wet season, a large portion of the runoff is infiltrated as well. However high percolation rates (more than 10 times that of the catchment) indicated that water draining into the soil does not undergo any type of natural filtration process. Therefore, groundwater contamination is potentially high. These findings indicate the importance of the consideration of IRES in city planning during urbanization, in the context of groundwater recharge, flood control, and siltation of reservoirs. In this regard, we emphasize that even treated wastewater should not be released into such dry stream beds to avoid groundwater contamination and no lining should be done to control floods and to avoid silting reservoirs. Alteration of the natural status quo of IRES in any manner would have adverse effects on the natural and built environment, and it is important that awareness and understanding of these streams are improved.
Importance of Leaving Intermittent Rivers and Ephemeral Streams (Ires) Untouched in a Sustainably Built Environment
Intermittent rivers and ephemeral streams (IRES) are temporary waterways that flow only at certain periods of the year and consist of more than half of the world’s total stream/river length. They have essential hydro-ecological functions and provide many ecosystem services but are widely ignored and considered as mere surface flow or trenches, and Sri Lanka is no exception. That is why we do not see such streams even in semi-urban townships, an indication that those have been either reclaimed or replaced with man-made (e.g., concrete-lined) drainages. In this study, we discuss the importance and sustainable management of IRES in the dry and intermediate climatic zone of Sri Lanka which has townships, extensive agriculture, tourism infrastructure, and where the built environment shows signs of expansion. A unique characteristic observed in IRES of the study area was their signature high infiltration at the stream bed (about 40 times that of the catchment), and somewhat high infiltrations in the low-flow areas. High infiltration of the beds contributes to groundwater recharge, where all rainfall received during the dry season (including runoff from the catchment) is infiltrated (therefore, no flow in the stream). To control flooding in the wet season, a large portion of the runoff is infiltrated as well. However high percolation rates (more than 10 times that of the catchment) indicated that water draining into the soil does not undergo any type of natural filtration process. Therefore, groundwater contamination is potentially high. These findings indicate the importance of the consideration of IRES in city planning during urbanization, in the context of groundwater recharge, flood control, and siltation of reservoirs. In this regard, we emphasize that even treated wastewater should not be released into such dry stream beds to avoid groundwater contamination and no lining should be done to control floods and to avoid silting reservoirs. Alteration of the natural status quo of IRES in any manner would have adverse effects on the natural and built environment, and it is important that awareness and understanding of these streams are improved.
Importance of Leaving Intermittent Rivers and Ephemeral Streams (Ires) Untouched in a Sustainably Built Environment
Lecture Notes in Civil Engineering
Dissanayake, Ranjith (editor) / Mendis, Priyan (editor) / Weerasekera, Kolita (editor) / De Silva, Sudhira (editor) / Fernando, Shiromal (editor) / Konthesingha, Chaminda (editor) / Gajanayake, Pradeep (editor) / Perera, M. D. D. (author) / Madhushani, T. M. C. I. (author) / Gomes, P. I. A. (author)
International Conference on Sustainable Built Environment ; 2022 ; Yogyakarta, Indonesia
2023-08-10
11 pages
Article/Chapter (Book)
Electronic Resource
English
Intermittent rivers and ephemeral streams , Infiltration; percolation , Groundwater recharge , Flood control Energy , Sustainable Architecture/Green Buildings , Environmental Policy , Sociology, general , Energy Policy, Economics and Management , Building Construction and Design , Sustainable Development , Engineering
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