A coastal planning team surveyed an estuary beside a small fishing village in southern Thailand. Fig. 1 is a field cross-section drawn from a tidal creek to...
Question 1 Report
A coastal planning team surveyed an estuary beside a small fishing village in southern Thailand. Fig. 1 is a field cross-section drawn from a tidal creek to the higher shore. It shows changes in ground level, sediment and vegetation across the mangrove landscape. The team wants to protect the site while allowing local people to use a marked boardwalk and collect shellfish. The scale bar in Fig. 1 is 100 m.
(a) Which section of the transect, A, B or C, is most likely to be flooded by seawater most often? [2]
(b) Draw a labelled arrow on a copy of Fig. 1 to show one route by which sediment could enter the mangrove area. Outline one reason why sediment is deposited there. [4]
(c) Explain how mangrove vegetation can reduce the effects of coastal erosion and provide benefits for people living near this tropical coastline. Use Fig. 1 in your answer. [9]
Answer Details
(a) A [1] because it is nearest the tidal creek / lowest section / is reached by tides first [1] (b) Arrow shown from tidal creek / sea towards mangrove roots or mudflat [1]. Any three from: water slows as it moves through roots [1]; reduced velocity lowers its carrying capacity [1]; suspended sediment settles / is deposited [1]; shallow, sheltered water encourages deposition [1]. (c) Any nine from: prop roots / dense root systems break up wave energy [1]; lower wave energy reduces erosion of the shore [1]; roots bind muddy sediment [1]; trapped sediment builds or maintains the coastal surface [1]; this can reduce flooding during high tides or storms [1]; mangroves act as a buffer between the sea and homes / paths [1]; vegetation provides nursery habitat for fish, crabs or shellfish [1]; this supports fishing livelihoods / food supply [1]; mangroves provide wood or other carefully managed resources [1]; boardwalks can concentrate visitors and reduce trampling of roots [1]; protected mangroves may attract ecotourism income [1]; management is needed because cutting trees or uncontrolled collection could damage the root barrier [1].
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