Potamological Studies on the River Ina of the River System of Yodo (IV)

猪名川中流部ゴルフ橋本・支流合流点で昭和48年1月から昭和51年4月まで,水温,pH及び4.3アルカリ度(HCO_3^-), Ca^<2+>, Cl^-, COD濃度の季節変化を観測した結果,以下のことが得られた。1.水温(Θw)は気温(Θa)との間に密接な相関があり,これらの回帰直線は次式のようである。2.4.3アルカリ度(HCO_3^-)とCa^<2+>,Mg^<2+>,Cl^-濃度間には密接な正の相関関係があり,HCO_3^-とCa^<2+>,Mg^<2+>濃度の回帰直線はほぼ原点を切っている。又その重量関係は次式に示すように一定比をとっている。HCO_3^-:(Ca^<2+>+Mg^<2+>)≒3:1 3.流量と溶存成分濃度の関係は,両対数紙上で全般に右下がりの直線又は曲線関係が認められる。pHは流量増加に伴ない減少し,中性に近づく。HCO_3^-,Ca^<2+>,Mg^<2+>,Cl^-濃度は,同一流量時には高温時に高く,低温時に低い。又低・渇水時には,HCO_3^-,(Ca^<2+>+Mg^<2+>),Cl^-濃度はそれぞれ約60mg/l,20mg/l,15mg/l前後のほぼ一定値に近づく。The seasonal variation of water temperature, pH and the concentration of 4.3-alkalinity (as HCO_3^-),.Ca^<++>, Mg^<++>, Cl^-, COD in river water have been observed at the Golf-Bridge in the middle of the Ina River Basin from January 21, 1973 to April 3, 1976 and from the results of observations some considerations were made for the trend of the variation of water quality and the relationship between the concentration of dissolved solids and water discharge. The aspect of the variation of water quality is as follows: 1. The relation between water temperature and air temperature measured at 10:00 o'clock a.m. is expressed by two straight lines. These regression lines of water temperature (Θa), on air temperature (Θa) have the next forms. Main stream Θw(℃)=0.48Θa+1.8 Tributary Θw(℃)=0.49Θa+3.3(Θa<16℃) Main stream Θw(℃)=1.0Θa-4.4 Tributary Θw(℃)=1.1Θa-7.0 (Θa>16℃) 2. The concentration of HCO_3^- has a close correlation with Ca^<++> and Mg^<++> concentration and the regression line passes practically through the coordinate origin with the inclination of 1/3 as is well known. The concentration of HCO_3^- has a possitive correlation with Cl^- concentration. 3. The negative relation expressed by a logarithmically straight or curved line was obtained btween the discharge and the concentration of dissolved solids. The concentration of HCO_3^-, (Ca^<++>+Mg^<++>)and Cl^- are about 60, 20 and 15mg/l respectively at low discharge and decreases with increasing discharge. For a given value of discharge, the concentrations are higher at the higher air temperature than at the lower air temperature. The value of pH decreases also with increasing discharge at the similar tendency of the variation of the concentrations and approaches gradually to the nuetrality