ENGG MG6011 Hydrology and Erosion Management

ENGG MG6011: Hydrology and Erosion Management

a. Calculate slope using the equal area method.
b. Briefly explain your choice of channelisation factor,C,used.

c. Briefly explain your choice of Curve Number(s), CN,used.

Table 1:Catchment imperviousness for pre- and post-development scenarios

3. Based on the existing slope and overland flow path route through the site, determine a suitable overland flow path dimension to allow the 100-yr flows to pass through the site. The slope ca lculation should be specific to the site,not the total contributing catchment.
a. Provide a sketch of the OLFP cross-section

b. Briefly explain your selection for channel side slopes.

c. Briefly explain your selection for manning's.

4. Describe three appropr iate water sensitive design elements that may be included in the proposal.AC GD04 (2015) may provide additional insight to that provided in
lectures.

a. Describe in your own words what water sensitive design is,and why we apply the principles in design.
b. Discuss the benefits that the three selected WSD elements can provide to the proposed development.
c. Discuss any challenges particular to the site that may restrict the use of WSD devices.
d. Discuss the particular suitability of the water sensitive design approach in terms of alignment with Tangata W henua values which are likely to be important to the users of this site.

e. Describe in detail suitable method of water quality treatment for the building roof and carpark. This treated water will discharge to the open channel.

2019 Assignment 1- Umupuia Marae Development Clevedon

A new office building and carpark are to be built on the grounds of the Umupuia Marae at
153 MaraetaiCoast Road,Clevedon.
The Marae at Umupuia is the Mana Whenua Marae of the Ngai Tai lwi of Umupuia and
Tamaki Makaurau. It is situated on ancestral land at Umupuia adjacent to the Wairoa River with Umupuia Beach immediately in front and hundreds of acres of Ngahere (native bush) behind,and as such is unique in the Auckland area.
The sacred values of water including its Mauri or life force is very important to the Ngai Tai people and as such there is a strong driver to adopt water sensitive principles for the proposed development.
The new office building will be to the northwest of the existing Marae and Church and South of the watercourse across the site,as indicated in Figure 1(taken from the Auckland Council GIS viewer).
A site diagram is shown in Figure 2. The available area set aside for development within the approx. 2,800m2 area shown on Figure 2. The site is underlain by clay and alluvial soils.A watercourse overland flow path flows through the site from the rural areas to the south west. It is assumed that the floodplain of the larger stream to the south will not spill into the subject site and catchment. The proposed office building is to have an area of 500 m2, and associated new site impervious of 1,000 m2 combined for proposed car parks,driveway(s)
and all footpaths connecting the building entries,parking areas, and existing facilities on the site.
It is assumed that soakage is unavailable at the site. As the runoff form carparking discharges to the coast, Unitary Plan requirements mean water quality treatment will be required for both car park (>SO vehicles per day) and roof runoff (assumi ng a metal roof, containing zinc) from both the office block and existing Marae and Church facilities.
Your job is to undertake the following tasks:

1. Define the upstream catchment contributing to overland flows leaving the site discharge point (Figure 2). Assume all reticulation is blocked for catchment definition i.e . define for the 100-yr AR Ievent. Assume that the floodpla in from the la rger stream to the south
does not connect and the catchment is that to the over la nd f lowpath to the site indicated in the Auckland council GIS as approximately 8.9 hecta res.
a. Provide a map of your catchment including display of the total catchment area.
b. Show the catchment slope length and a lignment on your pla n.
c. Provide a paragraph discussing constraints identified during your catchment definition.State any assumptions or decisions made while defining the catchment.