Case study:Chelmer Valley Local Nature Reserve - Revision history

Alexrrc at 13:55, 1 November 2018

2018-11-01T13:55:30Z

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	\|Main contact surname=Bond		\|Main contact surname=Bond
	\|Contact organisation=Environment Agency		\|Contact organisation=Environment Agency
			\|Contact organisation url=www.gov.uk/government/organisations/environment-agency
	\|Partner organisations=Essex Wildlife Trust		\|Partner organisations=Essex Wildlife Trust
	\|Multi-site=No		\|Multi-site=No

Alexrrc at 11:39, 1 November 2018

2018-11-01T11:39:19Z

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	\|Specific mitigation=Flood risk management,		\|Specific mitigation=Flood risk management,
	}}		}}
	{{Measures}}		{{Measures
			\|Bank and bed modifications measure=Creation of berms,
			\|Floodplain / River corridor=Lowering of embankments, Floodplain reconnection, Riparian habitat restoration,
			}}
	{{Hydromorphological quality elements header}}		{{Hydromorphological quality elements header}}
	{{End table}}		{{End table}}

Alexrrc at 11:38, 1 November 2018

2018-11-01T11:38:10Z

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	\|Invst and design cost=25000		\|Invst and design cost=25000
	}}		}}
	{{Motivations}}		{{Motivations
			\|Specific mitigation=Flood risk management,
			}}
	{{Measures}}		{{Measures}}
	{{Hydromorphological quality elements header}}		{{Hydromorphological quality elements header}}

Alexrrc at 11:37, 1 November 2018

2018-11-01T11:37:53Z

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	}}		}}
	{{Project background		{{Project background
			\|Total1 cost=£25k
			\|Funding sources=Catchment Partnership Action Fund,
	\|Investigation and design cost category=more than 10000 k€		\|Investigation and design cost category=more than 10000 k€
	\|Invst and design cost=25000		\|Invst and design cost=25000

Alexrrc at 11:37, 1 November 2018

2018-11-01T11:37:20Z

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	{{Case study subcatchment}}		{{Case study subcatchment}}
	{{Site		{{Site
			\|Name=Chelmer
	\|WFD water body code=GB105037033950		\|WFD water body code=GB105037033950
	\|Heavily modified water body=No		\|Heavily modified water body=No

Alexrrc at 11:36, 1 November 2018

2018-11-01T11:36:50Z

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	\|Project summary=Restoration of the River Chelmer upstream of Chelmsford City Centre by re-profiling the banks to increase in-channel morphological diversity, create additional marginal aquatic habitats, improve floodplain connectivity and create additional backwater habitats. <br>		\|Project summary=Restoration of the River Chelmer upstream of Chelmsford City Centre by re-profiling the banks to increase in-channel morphological diversity, create additional marginal aquatic habitats, improve floodplain connectivity and create additional backwater habitats. <br>
	The River Chelmer has historically been heavily modified to improve flood protection and land drainage. This has led to a uniform wide, straight, deep channel upstream of Chelmsford City Centre. This in tern has resulted in reduced plant diversity, and there has recently been deterioration in fish status.<br>		The River Chelmer has historically been heavily modified to improve flood protection and land drainage. This has led to a uniform wide, straight, deep channel upstream of Chelmsford City Centre. This in tern has resulted in reduced plant diversity, and there has recently been deterioration in fish status.<br>
	The Chelmer Valley Local Nature Reserve (LNR) is a much loved open space situated to the north of Chelmsford city centre (Map 1). Approximately 2.5km long, the Chelmer Valley LNR consists of parkland, green spaces, unimproved grassland, ponds, wet margins, riparian woodland and the River Chelmer itself (Photo 1).		The Chelmer Valley Local Nature Reserve (LNR) is a much loved open space situated to the north of Chelmsford city centre (Map 1 on project webpage). Approximately 2.5km long, the Chelmer Valley LNR consists of parkland, green spaces, unimproved grassland, ponds, wet margins, riparian woodland and the River Chelmer itself (Photo 1).
	As part of this project, informal embankments created through years of dredging were lowered and the won material was used within the river to construct earth berms. This improved floodplain connectivity, created marginal habitat for plants and restricted the width of the active river channel, encouraging geomorphic processes. In addition, flood risk modelling of the scheme has shown flood risk benefits emerging from the project during particular flood frequencies. Flood risk modelling indicated that the scheme would lead to a small, net decrease in lateral flood extent during both 10% and 1% annual exceedance probability (AEP) events. Modelling also suggests reduced flood depths of up to 0.3m in some locations during a 10% AEP event and reduced flood depths of 0.15m in some locations during a 1% AEP. The reduced flood risk is believed to be due to the improved connectivity between the main river channel and the floodplain, which means water evacuates onto the floodplain earlier and the flood peak is marginally reduced.		As part of this project, informal embankments created through years of dredging were lowered and the won material was used within the river to construct earth berms. This improved floodplain connectivity, created marginal habitat for plants and restricted the width of the active river channel, encouraging geomorphic processes. In addition, flood risk modelling of the scheme has shown flood risk benefits emerging from the project during particular flood frequencies. Flood risk modelling indicated that the scheme would lead to a small, net decrease in lateral flood extent during both 10% and 1% annual exceedance probability (AEP) events. Modelling also suggests reduced flood depths of up to 0.3m in some locations during a 10% AEP event and reduced flood depths of 0.15m in some locations during a 1% AEP. The reduced flood risk is believed to be due to the improved connectivity between the main river channel and the floodplain, which means water evacuates onto the floodplain earlier and the flood peak is marginally reduced.
	\|Monitoring surveys and results=Increasing the diversity of the channel provide different habitats to support a wider diversity of plants and animals. Fish bays provide shallow, slower flowing, warmer water preferred by small fish and fry.		\|Monitoring surveys and results=Increasing the diversity of the channel provide different habitats to support a wider diversity of plants and animals. Fish bays provide shallow, slower flowing, warmer water preferred by small fish and fry.

Alexrrc at 11:36, 1 November 2018

2018-11-01T11:36:11Z

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	\|Multi-site=No		\|Multi-site=No
	\|Project picture=6 Chelmer.png		\|Project picture=6 Chelmer.png
	\|Project summary=Restoration of the River Chelmer upstream of Chelmsford City Centre by re-profiling the banks to increase in-channel morphological diversity, create additional marginal aquatic habitats, improve floodplain connectivity and create additional backwater habitats.		\|Project summary=Restoration of the River Chelmer upstream of Chelmsford City Centre by re-profiling the banks to increase in-channel morphological diversity, create additional marginal aquatic habitats, improve floodplain connectivity and create additional backwater habitats. <br>
	The River Chelmer has historically been heavily modified to improve flood protection and land drainage. This has led to a uniform wide, straight, deep channel upstream of Chelmsford City Centre. This in tern has resulted in reduced plant diversity, and there has recently been deterioration in fish status.		The River Chelmer has historically been heavily modified to improve flood protection and land drainage. This has led to a uniform wide, straight, deep channel upstream of Chelmsford City Centre. This in tern has resulted in reduced plant diversity, and there has recently been deterioration in fish status.<br>
	The Chelmer Valley Local Nature Reserve (LNR) is a much loved open space situated to the north of Chelmsford city centre (Map 1). Approximately 2.5km long, the Chelmer Valley LNR consists of parkland, green spaces, unimproved grassland, ponds, wet margins, riparian woodland and the River Chelmer itself (Photo 1).		The Chelmer Valley Local Nature Reserve (LNR) is a much loved open space situated to the north of Chelmsford city centre (Map 1). Approximately 2.5km long, the Chelmer Valley LNR consists of parkland, green spaces, unimproved grassland, ponds, wet margins, riparian woodland and the River Chelmer itself (Photo 1).
	As part of this project, informal embankments created through years of dredging were lowered and the won material was used within the river to construct earth berms. This improved floodplain connectivity, created marginal habitat for plants and restricted the width of the active river channel, encouraging geomorphic processes. In addition, flood risk modelling of the scheme has shown flood risk benefits emerging from the project during particular flood frequencies. Flood risk modelling indicated that the scheme would lead to a small, net decrease in lateral flood extent during both 10% and 1% annual exceedance probability (AEP) events. Modelling also suggests reduced flood depths of up to 0.3m in some locations during a 10% AEP event and reduced flood depths of 0.15m in some locations during a 1% AEP. The reduced flood risk is believed to be due to the improved connectivity between the main river channel and the floodplain, which means water evacuates onto the floodplain earlier and the flood peak is marginally reduced.		As part of this project, informal embankments created through years of dredging were lowered and the won material was used within the river to construct earth berms. This improved floodplain connectivity, created marginal habitat for plants and restricted the width of the active river channel, encouraging geomorphic processes. In addition, flood risk modelling of the scheme has shown flood risk benefits emerging from the project during particular flood frequencies. Flood risk modelling indicated that the scheme would lead to a small, net decrease in lateral flood extent during both 10% and 1% annual exceedance probability (AEP) events. Modelling also suggests reduced flood depths of up to 0.3m in some locations during a 10% AEP event and reduced flood depths of 0.15m in some locations during a 1% AEP. The reduced flood risk is believed to be due to the improved connectivity between the main river channel and the floodplain, which means water evacuates onto the floodplain earlier and the flood peak is marginally reduced.

Alexrrc at 11:35, 1 November 2018

2018-11-01T11:35:47Z

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	{{Case study status		{{Case study status
	\|Approval status=~~Draft~~		\|Approval status=Approved
	}}		}}
	{{Location		{{Location

Alexrrc at 11:35, 1 November 2018

2018-11-01T11:35:32Z

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	{{Project overview		{{Project overview
	\|Status=Complete		\|Status=Complete
	\|Themes=Habitat and biodiversity, Hydromorphology, Water quality		\|Project web site url=www.therrc.co.uk/sites/default/files/projects/6_chelmer.pdf
			\|Themes=Flood risk management, Habitat and biodiversity, Hydromorphology, Social benefits, Water quality
	\|Country=England		\|Country=England
	\|Main contact forename=~~Matt~~		\|Main contact forename=Trev
	\|Main contact surname=~~Butcher~~		\|Main contact surname=Bond
			\|Contact organisation=Environment Agency
			\|Partner organisations=Essex Wildlife Trust
	\|Multi-site=No		\|Multi-site=No
			\|Project picture=6 Chelmer.png
	\|Project summary=Restoration of the River Chelmer upstream of Chelmsford City Centre by re-profiling the banks to increase in-channel morphological diversity, create additional marginal aquatic habitats, improve floodplain connectivity and create additional backwater habitats.		\|Project summary=Restoration of the River Chelmer upstream of Chelmsford City Centre by re-profiling the banks to increase in-channel morphological diversity, create additional marginal aquatic habitats, improve floodplain connectivity and create additional backwater habitats.
	The River Chelmer has historically been heavily modified to improve flood protection and land drainage. This has led to a uniform wide, straight, deep channel upstream of Chelmsford City Centre. This in tern has resulted in reduced plant diversity, and there has recently been deterioration in fish status.		The River Chelmer has historically been heavily modified to improve flood protection and land drainage. This has led to a uniform wide, straight, deep channel upstream of Chelmsford City Centre. This in tern has resulted in reduced plant diversity, and there has recently been deterioration in fish status.
			The Chelmer Valley Local Nature Reserve (LNR) is a much loved open space situated to the north of Chelmsford city centre (Map 1). Approximately 2.5km long, the Chelmer Valley LNR consists of parkland, green spaces, unimproved grassland, ponds, wet margins, riparian woodland and the River Chelmer itself (Photo 1).
			As part of this project, informal embankments created through years of dredging were lowered and the won material was used within the river to construct earth berms. This improved floodplain connectivity, created marginal habitat for plants and restricted the width of the active river channel, encouraging geomorphic processes. In addition, flood risk modelling of the scheme has shown flood risk benefits emerging from the project during particular flood frequencies. Flood risk modelling indicated that the scheme would lead to a small, net decrease in lateral flood extent during both 10% and 1% annual exceedance probability (AEP) events. Modelling also suggests reduced flood depths of up to 0.3m in some locations during a 10% AEP event and reduced flood depths of 0.15m in some locations during a 1% AEP. The reduced flood risk is believed to be due to the improved connectivity between the main river channel and the floodplain, which means water evacuates onto the floodplain earlier and the flood peak is marginally reduced.
	\|Monitoring surveys and results=Increasing the diversity of the channel provide different habitats to support a wider diversity of plants and animals. Fish bays provide shallow, slower flowing, warmer water preferred by small fish and fry.		\|Monitoring surveys and results=Increasing the diversity of the channel provide different habitats to support a wider diversity of plants and animals. Fish bays provide shallow, slower flowing, warmer water preferred by small fish and fry.
	Blackwater habitats increase habitat diversity, whilst providing a refuge for fish and invertebrates from high flows.		Blackwater habitats increase habitat diversity, whilst providing a refuge for fish and invertebrates from high flows.
	The banks and channel of the main river were re-profiled at 9 locations. The river bank was lowered to re-connect the river to its natural floodplain, improving marginal and riparian wetland habitats. Improving connectivity between the river and floodplain allows sediment to settle out on the floodplain, and fish and invertebrates to escape from the highest flows in flood events By storing water on the floodplain sooner, downstream flood risk can also be reduced. The bank material was pushed into the channel, creating earth berms. These narrow the channel during low flows, increasing water velocity. This helps other river processes such as sediment transfer, erosion and depositing and oxygenation of the water, which creates habitats and improves water quality. The berms also create diversity of marginal and aquatic habitats, which was previously very uniform. In addition, shallow bays were created and a backwater improved to provide additional habitat for fish and fry.		The banks and channel of the main river were re-profiled at 9 locations. The river bank was lowered to re-connect the river to its natural floodplain, improving marginal and riparian wetland habitats. Improving connectivity between the river and floodplain allows sediment to settle out on the floodplain, and fish and invertebrates to escape from the highest flows in flood events By storing water on the floodplain sooner, downstream flood risk can also be reduced. The bank material was pushed into the channel, creating earth berms. These narrow the channel during low flows, increasing water velocity. This helps other river processes such as sediment transfer, erosion and depositing and oxygenation of the water, which creates habitats and improves water quality. The berms also create diversity of marginal and aquatic habitats, which was previously very uniform. In addition, shallow bays were created and a backwater improved to provide additional habitat for fish and fry.
	\|Lessons learn=Early communication with permitting bodies and involvement of local communities is essential to deliver successful projects in a short timescale.		\|Lessons learn=Early communication with permitting bodies and involvement of local communities is essential to deliver successful projects in a short timescale.
	}}		}}

Alexrrc at 11:30, 1 November 2018

2018-11-01T11:30:18Z

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	\|Approval status=Draft		\|Approval status=Draft
	}}		}}
	{{Location}}		{{Location
			\|Location=51.7447939, 0.4739537000000382
			}}
	{{Project overview		{{Project overview
	\|Status=Complete		\|Status=Complete