Green Roads for Water

Page 137

Roads for Water in Mountain Areas | 113

TABLE 6.2  Effect

of road development on different types of springs

SPRING TYPE

DESCRIPTION

EFFECT OF ROAD DEVELOPMENT

Springs with concentrated discharge (through one or more orifices) Fracture spring

Faults, fractures, and cleavage in semipermeable and permeable formations connected with a water source (seepage, flow,,shallow or deep aquifer)

Road development may expose the spring; rock cutting may change the location of the orifices, either blocking old or creating new ones.

Contact spring

Permeable layer overlays an impermeable layer, forcing water to come out, often in a line of springs

Road may distort the outflow of the spring, causing orifices to be blocked or new ones to be created; highly dependent on geological faulting.

Fault spring

As a result of geotectonic movement, a permeable layer is moved on top of an impermeable layer

Road may distort the outflow of the spring, causing orifices to be blocked or new ones to be created; highly dependent on geological faulting.

Depression spring

The groundwater table reaches the surface in topographical low point

Road may create new depression springs where the roads are made in cut, or it may create dry existing springs by lowering the groundwater table.

Karst spring

Relatively large flow from large openings, typically in karst areas where water erodes the calcium formation

Roads may expose new springs and expose new cavities.

Springs with diffuse discharge Seep

Diffuse direct discharge of water, usually from soils or unconsolidated sediments (sand or gravel)

Road development may create many seeps, especially where roads are developed in areas with deep soil profiles.

Secondary springs

Water issued from a primary spring that is typically covered by debris or rock fall

Road development may expose springs or change the outlet, particularly where unconsolidated material is removed.

Source: MetaMeta (www.roadsforwater.com).

Table 6.2 shows the effect of the opening of a new road alignment on different spring types. The development of roads may distort existing springs but may also create new ones. Given the importance of springs for domestic water supply or agricultural use, the management of mountain springs in road development should be an integral part of road construction. Springs and seeps are also main sources of road damage (photo 6.4), either by affecting the road surface directly or by creating minor depressions in the roads that grow during the monsoon and cause uncontrolled and erosive runoff from road bodies. There are several types of springs. Geomorphology, rock type, and tectonic history determine the type of spring that occurs. Two broad categories are springs with concentrated discharge through one or more clear orifices, and springs with more diffuse discharge. Table 6.2 shows the effect of road development on the different types of springs. Managing the springs along mountain roads is important for safeguarding road quality and ensuring water supply for domestic and agricultural use. Before a road is built, the geology must be understood and the areas where springs occur or are likely to occur should be mapped. When roads are being constructed, they affect the location of springs if not handled carefully. The use of bulldozers or excavators in areas of potential springs should be avoided; manual labor should be used to excavate the road in such sections. Once the road is developed, the presence of springs and seeps will be evident and whether the spring or seep will be used must be determined. In areas with low population densities, springs may not be used, but they should still be managed to prevent discharge from damaging the road body. Table 6.3 suggests methods for managing different types of springs in different circumstances.


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Ethiopia

3min
pages 254-255

A.1 Making a community map

1min
page 262

15.3 Road maintenance group using work safety measures, Nepal

1min
page 256

A.2 Transect walk

1min
pages 263-265

15.2 How to engage communities in road development

4min
pages 252-253

15.1 Different stages in community engagement

12min
pages 246-250

Examples of community engagement at scale

2min
page 251

15.1 The scope for community engagement under different roads programs

5min
pages 243-244

water sector, agriculture, and universities, Malawi

1min
page 237

Note

1min
pages 239-240

Scope for community engagement

2min
page 242

for road programs

2min
page 238

Getting the process going Annex 14A. Sample supplemental terms of reference

2min
page 236

Governance for roads for water

2min
page 232

Conclusions

6min
pages 222-223

of seedlings

1min
page 220

Combining water harvesting and tree planting

3min
pages 217-218

12.2 Roadside tree barriers and dust movement

1min
page 216

Design of roadside vegetative barriers

2min
page 215

12.1 Roadside vegetation and road safety measures

1min
page 213

12.1 Tree planting and road visibility

1min
page 212

Opportunities

2min
page 209

Site selection

2min
page 211

Recommended practices

1min
page 210

11.1 Infiltration rates of different soils

7min
pages 197-199

References

1min
pages 205-206

11.3 Suitable pond side slopes for different soils

6min
pages 202-204

References

1min
page 192

Recommended practices

1min
pages 195-196

10.3 Rolling drainage dip in low-volume road

1min
page 190

Opportunities

2min
page 183

Recommended practices

8min
pages 184-187

8.1 Geotextile materials for reservoir lining

1min
page 169

Opportunities Recommended practice: River crossings as sand dams and bed

1min
page 172

9.2 Overview of nonvented drift with preventable failure features

1min
page 178

Recommended practices

13min
pages 162-168

Opportunities

2min
pages 160-161

Recommended practices and preferred options

5min
pages 149-151

7.1 Road culvert spacing and dimensions for floodplains

6min
pages 152-154

Alternative road option in floodplains: Submersible roads

1min
page 155

References

1min
pages 145-146

Opportunities

1min
page 148

Notes

2min
page 144

6.7 Technique for creating artificial glaciers in mountain areas

2min
pages 142-143

6.6 Snowshed in Alpine environment

1min
page 141

6.3 Recommended practices for spring management along roads

1min
page 138

6.4 Infiltration bunds

1min
page 136

6.2 Effect of road development on different types of springs

3min
page 137

5.2 Minimum cross-drainage opening for Bangladesh lowlands

9min
pages 110-115

routes

4min
pages 120-122

Changing the mountain environment

2min
pages 127-128

6.2 Tilted causeways

1min
page 134

6.3 Dissipation block placement on the road

1min
page 135

Opportunities

4min
pages 104-105

Recommended best practices

2min
page 106

3.1 Typical concentrations of pollutants in highway runoff

2min
page 65

4.11 Water-spreading weir, Ethiopia

1min
page 100

Kotomor, Agago (northern region, Uganda

1min
page 99

4.2 Fodder grown from road culvert water, South Gondar, Ethiopia

1min
page 87

Techniques for road-water harvesting

2min
page 89

Road safety principles

2min
page 88

Amhara, Ethiopia, 2018

1min
page 85

3.2 Roadside spring with inadequate collection reservoir, Sardinia, Italy

1min
page 76

Recommended practices

9min
pages 66-69

Opportunities

2min
page 64

Notes

1min
page 60

References

2min
pages 61-62

2.4 V-shaped floodwater spreader

4min
pages 58-59

harvesting

3min
page 57

Recommended practices

2min
page 51

References

2min
pages 43-46

The three levels of promoting resilience: Protective, adaptive, and proactive

2min
page 34

3 Drift construction in sand river bed: General section of nonvented

2min
page 33

Road safety considerations

5min
pages 41-42

The benefits and costs of roads for water

2min
page 35

1.2 Three levels of road resilience for different road elements

2min
page 37

2 Community mobilization for road-water harvesting in Amhara

2min
page 39

3 Roadside spring opened after road construction in Tigray, Mulegat

1min
page 27

Changing the paradigm: Concept and principles of roads for water

4min
pages 31-32
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