PROBLEM OF RIVERS.

Pukekohe & Waiuku Times, Volume 1, Issue 93, 16 May 1913, Page 4

PROBLEM OF RIVERS.

Deforestation And its Effects.

Mr E. T. Fi'o-f, of Tuakau, writes:— "In a cfimpurauvely small country like New Zealand the rapid denudation Ol itd furest will have a (lefii ite and marked effect in its streams and rivers, aid it vvc are wise wa will pause and consider ere it is too late. A good many ot the older settlers will no doubt remember ths fine streams that abounded before the bush was all cl-.ared, ar.d t at even in (be drie t summer t; ere was always plenty of water, whereas row tie same streams have dwii died do.vn t;5 a mere trickle, atd h fomo cases havo complete ly dried up. " Fhe main contributing came is that owing to the land being cleared of it 3 natural growth the rainfall does ret find its way to the streams by filtration, but mcst of it ia lost ly evaporati n. If the rainfall is txcetsive at iimes the sirejm is a i'cgirg io'rtnt for a few inure, but all too soon it dwindles away. "What h£pp.n3 to creeks in a tmall way will sconei or later be felt m the rivers. In view cf the p ejected improvements on the Waika!o river it will bo interesting to note what effect riefarcstntion would have cn it. Tr.e great trouble i;i the Waikato is the silt or sanu which is brought intj it 3 bed by tributary streams, lbe greatest amount cf this is bruught down in the wettest months cf the year and if the Cjiintry adjoining lha main ttibutaries H denuded of its forest, a greater ? incur; t of eilt will be carried down than tormeily, cwing to the greater eio.ion which takes place. This is patent to at.yone who Kill take notice, a3 witness Ic' e large s:umber cf land slips which take phca when lar.d is cleared cn tha steep slop.-a. This I throws more work cn the river to i k.ey it:Uf a lair 1 v cl:ar discharge chanrel, and there are t : m s, after Jan exceptionally wet s asou, when the river will take a while to accommodate it«lf to the new conditions trcught abeut by the extra amount of silt carried into it-j b:d. Consequently, the sand i 3 always more tioublesorna to navigation after a flood ha 3 subsided than at any ether time, bacausa the river has net qmie Bccomn.cdaUd its" If to the t'XCi.'S 0? silt. "Then in adrysea.on we find that the river, like the aforementioned creek 3, curries '.ess water down than form:rly, ar.d thij tricars that the current runs less ewift; it consequently cannot hold so much solid matter in suspension and thus more deposit is encouraged. Tha tide also will have the effect of slackening the current for a greater distance up from it 3 inouth, ar.d the lower reaches will gradually get shallower. "Ihera are portions of the coir.try sdjoining tie river whicn no (Jtvernmer.t shoulJ have parleJ wi h. Ihey shoul.! have beau preserved for climatic reasors. "In the United States they a:e paying riearly in places for doing what this Dominion is doing, and have had to turn their attention to the a!forcsta!i n of the watershed s of sim: cf their rivers. Let us hope that we do not go so far and that the matter will be taken up in time. It is {leasing to note that the For; sirs Commission is keeping something of this in hand, and r.o dtubt w'll in dm course n:aka some recorame: dntiun on tha rnaiter."