Show i t Geological Survey Makes Strong Case That the forest cover of the White Mountains has a distinct and measurable measurable me-asur- me able ablo effect upon the navigable streams which head in that region is tho the unequivocal unequivocal un un- equivocal l and emphatic statement o otho of tho United States Geological Survey The Director of the Survey las has m filed d his preliminary report on the White Mountains with the tho National Forest Reservation Commission and the findings are favorable to the purchase of lands lauds under the Weeks law The rhe report is based on the r results of exhaustive investigations and aud ape ape- specific specific field tests which have have been carried carried carried car car- ried on durin during the last year While the Survey has been subjected to frequent frequent fre Ire quent criticism and even bitter attacks attacks attacks at- at tacks owing to its r refusal to submit a perfunctory report assuming that a a. known and definite relation exists between forests and stream flow in inthe inthe the White Mountain region the out I come of its investigations must noti not i only satisfy the most radical forest enthusiast t but it precludes the possibility possibility possibility pos pos- of criticism by those thode who have opposed the acquisition by the government government government gov gov- of any forest lands on the theory that forest preservation does not affect stream flow The investigations investigations are believed indeed to solve definitely a problem that has long been boen a source of strenuous contention among scientists including the friends of forest conservation and while these investigations have direct refer refer- reference ence enee to the entire White Mountain area they establish a principle which is of far wider application The Weeks Forest Reservation Law places upon the Geological Survey the responsibility of establishing before before be be- e- e fore purchase the fact that forest lands have an effect upon the navigability ot of navigable streams and the law Jaw provides that the Survey shall make a field examination of every tract offered to the government for sale The Survey has insisted insisted in in- on following the tine plain mandate of the law and making such examinations examinations examina- examina not at an office desk but actually actually actually actu actu- ally on the ground in a thoroughgoing ing scientific manner in the southern Appalachian mountains moun moun- tracts aggregating acres have been certified to by the Geological Survey as affecting the navigability of streams by reason of the excessive erosion which follows deforestation In hi these areas Owing to co the geologic conditions in in the White Mountains no excessive erosion erosion erosion ero ero- sion according to the Survey geologists geologists can be shown to follow defor- defor Therefore the Survey carried carried carried car car- ried forward its further investigation in the White Mountains along the lines of trying to show that deforestation tion and subsequent burning of th the forest mulch results in a more moro rapid run-off run and therefore tends to make unstable the flow of streams The fhe hydrometric showing presented in the preliminary report covers covers results results re re- suits on two small almost exactly similar drainage basins of ab abo 5 square miles each each-cm e of iver one largely clothed d with virgin timber Umber and theother theother the theother other deforested and ana burned The facts observed d are so striking as to render the position of the Survey impregnable im im- pregnable Careful measurements of precipitation over the areas and of the run off of the respective ive streams show that not only was the snow held better in the forested area but that during a period of 17 days in April including three extended storms the run off of the of-the the stream in the deforested deforest deforest- ed area was a comparative flood flood- practically double that of the stream flowing through the forested area rea as shown below inches run off of Shoal Pond Brook forested area during three storms in April 1912 1287 inches ruu run off off of Burnt Brook deforested area during same storms In the Shoal Pond Brook basin the forested area the Survey established 7 rain gages and 26 20 20 snow gages and the engineers visited ed these continual continually ly during the tine winter on snowshoes the snow being from from 4 to 7 feet feat deep in the adjoining Burnt Brook basin the deforested area it established 9 rain gages and 18 snow gages On both streams hydrometric stations were established and the stream flow determined with a high degree of ac no- curacy The Survey report shows that the maximum flood flow from the forested basin was only 67 percent per percent percent cent of that from the deforested basin During the period of these thesa storms storm Burnt Brook deforested contributed a much greater volume of water to River than did Shoal Pond Brook forested The stream of the forested basin is observed to tobe tobe tobe be the st steadier adier of the two and in proportion proportion proportion pro pro- portion to its drainage area it tends tends- at least durin during the thA spring months months to to promote a flow of water inthe Inthe in inthe the mast master r stream of whist it is a tributary The conclusions of oi Director Geor George e eOtis Otis Smith of the Survey are as follows follows fol fol- lows x par two etwo son between en ad- ad t o S 'S SJ i i i r- r H h. h w. w jacent ba basins ins during critical periods period is presented pre in this preliminary statement statement statement state state- ment as a sufficient showing for the purposes of If the National Forest Reservation Reservation Reservation Res Res- Commission Whilo While data covering longer periods period for both these and other basins in the White Mountains Mona Moun talus have been collected and will be available a for the more complete report report report re re- re- re port the LI-Je particular case of the Burnt Brook and Shoal Pond Brook basins is t 13 typical for the region and establishes establishes etab- etab lishes the general conclusion that a SI direct relation exists he between tween forest cover and stream regulation The liThe results of the Burnt Brook Brook- Shoal Pond Brook studies are held to show that throughout the White Mountains Mountains Moun Moun- the removal of forest growth growth- must be expected to decrease the natural steadiness of dependent streams during the spring sprin months at least The foregoing conclusion forms a strong basis for arguing the desira desirability desirability of painstaking methods of administration administration administration ad ad- ministration in respect to forest lands in the White Mountain region Deforestation Deforestation De De- De- De forestation followed by fires as in ill inthe inthe the Burnt Brook basin results in conditions unfavorable to natural spring storage because conductive to rapid snow melting and stream run run- off Control of White Mountain lands that would reduce fires to a minimum and promote normal reforestation must result in a great improvement over present tendencies and this Improvement improvement improvement im im- Im- Im provement in forest cover over can logically logically logically logi logi- cally be expected to favorably affect stream regulation to the extent quantitatively quantitatively quantitatively quan quan- indicated in the comparison of the forested Shoal Pond Brook with the deforested Burnt Brook While the extensive hydrometric work was confined to a few headwater head bead water tributaries of the Connecticut and Merrimac rivers the basins i studied were selected aa as typical for forthe forthe forthe the whole White Mountain area and the field examinations over this region have shown the tracts now under con consideration consideration consideration for purchase to be similar to the basins bains here reported upon Therefore the favorable showing of this thill report is of general application in the White Mountain area Such an actual demonstration and measure of the performance perform perform- ance of different areas some forested and others defor deforested sted has never been Jeen attempted in trying to determine determine determine deter deter- mine the effect of forest cover on stream flow Efforts to arrive at definite denice de nite nice conclusions have always been based on a a. study of l long ng time records of precipitation and stream discharge but owing to the many qualifying factors such efforts have simply resulted resulted re re- re- re in divergent opinions and and- andin inconclusive inconclusive inconclusive in in- conclusive controversies The results of the present actual measurements in these mimic drainage basius basins so accurate and refined in method as to approach laboratory experiments where exact results may be expected leave no doubt as to to the conclusion Forest cover and th the resulting forest lorest I mat in the tha White Mountain granite area does to a considerable and I measurable degree e steady and regulate regulate regu regu- regu-I regu late stream flow and therefore must be stated as an i im important b t t-faut r in main maint g the Jie navigability of e ms whose headwaters headwaters' lie in such areas Bulletin Geological Survey |