Manawhai-Pakiri- UNINTENTIONAL CHANGES

Question 1

What economic activity is occurring?

Answer 1

Sand= essential mineral resource for construction, beach replenishment and glass manufacturing
- High quality sand resource on east coast suitable for CONSTRUCTION INDUSTRY
-> convenient as only 50km away from Auckland (1/2 NZ pop. and 35% of counties GDP)

Question 2

What did they do to Mangawhai??

Answer 2

Nearshore sand dredged 75000m^2/yr extraction used to replenish tourist beaches and economic development of Auckland

Question 3

What unintentional impacts were caused?

Answer 3

CLOSED SYSTEM AND RELICT SUPPLY => SAND TAKEN AWAY NOT REPLACED
-decreased movement of sand between major stores
-LT shoreline changes/coastal defences depleted
- decreased natural protection from extreme storm events

Question 4

Retreat speed?

Answer 4

35m by 2100

Question 5

Problem with Pakiri beach?

Answer 5

relict supply. INPUTS:OUTPUTS= 1:5
- sediment from FT => -ve sediment budget
-beaches self repair mechanism lost when starved of sediment -> wider and flatter

Question 6

Impacts on coastal landforms

Answer 6

Movement of sand between major stores decreases => beach starved of sediment => flatter => less effective in absorbing water => high energy waves in storm events erode beach and will damage landforms
- alters tidal currents => flooding in harbour
- dunes gain ridges from undercutting and loss of vegetation => suseptable to wind erosion