Jelgava, Latvia June 2016 iWater summer course
iWater Summer School 2016
Group Jelgava_1:
Marta Dambrova,
Matiss Priede,
Luís Rodrigues,
Aivars Berzins
The first information about goals of iWater project was received in a special book for each pilot site and introduction lectures.
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We were split in groups and every group received description of pilot site to work with. Information in written form and introduction by local municipality representative.
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Right after introduction we had an opportunity to visit the site and ask questions to representative of municipality.
We were working with the site in Jelgava city – Svete river floodplain. Total area of the site was 95 ha which consists of rivers and ponds (4.5 ha), housing area (39.8 ha), green and other area (50.7 ha). Total drainage basin 382 ha.
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According to information received during introduction we did several analysis. As the result we created maps of analysis for: physical and functional connections (green connections, transport, infrastructure), physical and ecological environment (landform and soils, hydrology and floodable areas, ecological values), land use and ownership, description of existing water management infrastructure. We did clarify the main concerns and problems of the site, so we could define main goals and problems to solve.
As the result it was clear that main problem of the area is flood period in spring and low quality existing water management system – mainly ditch system maintenance and system as itself in private housing area. The storm water runoff was not main problem for this area, but, of course, we had to take in consideration calculations of average storm water runoff.
After phase of research and analysis we were introduced with tools to use for solving the problem. The first step was to generate different sketches, ideas, management plans, design for the area in order to create main proposal. We set guidelines for two concepts to solve the main problem - flooding. Both concepts include solution - flow reduction in Svete river - otherwise high speed of water flow create flooding risk during the spring. The concepts split area into 4 functional zones: Residential, Transfer, Border, Nature. The water flow functions accordingly in each of zones:
Residential – drainage, infiltration, minimal purification, minimal retention
Transfer – purification, detention, flood protection
Border – inflow
Natural – water cycle
The difference of concepts were in Transfer part. Concept 1 was idea to create pond system that reduce flow and collect water, so the water passes smoothly through the area. Concept 2 was to create wider canal and hollow in Transfer zone that gives space for water to overflow in the area without damaging residential part.
Both concepts include:
- new and efficient stormwater infrastructure in residential part;
- recreational function in Transfer zone for residents and visitors of the city;
- existing river is left untouched to preserve natural values and biodiversity;
- educational function in Natural zone.
After presentation of concepts and discussion with tutors pond system concept was chosen to develop as a main proposal. The following work included to develop more detailed plan including description of solutions, details, functions, calculations, sections and master plan.
The residential area infrastructure was created in details including road types, stormwater solutions – ditches, swales, vegetated detention basins, rain gardens, additional trees and shrubs.
Transfer zone transformation in pond system and recreational area including pathways, view platforms, rain gardens, constructed wetland and efficient greenery.
Border zone was not changed as it is highest part of pilot site. The function of this area is to reduce water flow and also serve as a border between residential and natural parts.
Natural zone offers educational function for visitors, preservation of natural values and existing river path.
In general this was dynamic teamwork within the group and cooperation with tutors to create efficient solution in short period of time. We gained knowledge, learned new tools and realized the great importance of stormwater management.
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