Issued: 8-AUG-2008 CZECH HYDROMETEOROLOGICAL INSTITUTE Central Forecasting Office Drought information July 2008 was normal in the meaning of average temperature (+0,7 C above normal) as well as precipitation (1 % below normal) in the Czech Republic. However more precipitation has occurred in the eastern part of the area. Majority of precipitation events were connected to thunderstorms. That means that its spatial extent was usually relatively small and its duration was rather short. That kind of precipitation is not suitable for infiltration and underground water recharge. Precipitation caused temporal increase of water levels of streams in Odra river and Bečva river basins, while water levels of other streams in the Czech Republic were stable or slowly decreased. However due to precipitation a top soil moisture generally did not reach critical values of drought risk (fig.1) and wild fire risk (fig.2) except southern Moravia, eastern Bohemia and some areas in central Bohemia. Fig. 1 Drougth risk: 1 very low, 2 - low, 3 - moderate, 4 - high, 5 very high. Composite result of soil moisture measurement, computed soil water balance and evapotranspiranspiration balance.
Fig. 2 Wild fires risk: 1 very low, 2 - low, 3 - moderate, 4 - high, 5 very high. Surface streams and rivers discharges equal mostly to 20-50 % of long time average for August (Q VIII ). Mountainous rivers and streams have 50-80 % Q VIII. On the other hand some smaller lowland and middle altitudes streams in Bohemia discharge correspond only to 5-20 % Q VIII. Orlice river basin, Výrovka river, lower Cidlina River, Lomnice river, Skalice river and other could be named as examples. Value of so called Q 355 is considered to be drought threshold for river discharge. Q 355 represents about 3-5 % of historically lowest observations. Rivers below that threshold are indicated by white circle on the web presentation of CHMI (http://hydro.chmi.cz/hpps), fig.3 and table 1. Fig. 3 White dots indicate water gauges bellow the threshold for drought.
Tab. 1 water gauges bellow the threshold for drought ---------------------------------------------- RIVER WATER GAUGE LEVEL DISCHARGE N/M ---------------------------------------------- LABE JAROMER 69 4.60 355 METUJE KRCIN 16 1.22 355 D.ORLICE KOSTELEC no 16 1.32 364 TREBOVKA HYLVATY 24 0.19 355 T.ORLICE CERMNA no 11 0.65 365 ORLICE TYNISTE no 50 3.48 364 DEDINA CHABORY 19 0.07 365 DEDINA MITROV 14 0.07 365 CHRUDIMKA SVIDNICE 10 0.54 355 CHRUDIMKA NEMOSICE 38 0.84 355 DOUBRAVA ZLEBY 19 0.20 355 CIDLINA SANY 5 0.12 364 MRLINA VESTEC 4 0.07 364 VYROVKA PLANANY 10 0.01 365 JIZERKA D.STEPANICE 70 0.19 355 JIZERA ZELEZ. BROD 105 4.08 355 JIZERA PREDMERICE 116 6.64 355 LABE BRANDYS nl 127 27.00 355 NEZARKA RODVINOV 14 0.37 355 NEZARKA LASENICE 32 0.73 355 LUZNICE KLENOVICE 19 3.50 355 OTAVA SUSICE 24 3.36 355 BLANICE HERMAN 17 1.11 355 OTAVA PISEK 44 4.82 364 LOMNICE D. OSTROVEC 32 0.02 364 SKALICE VARVAZOV 60 0.06 364 KOCABA STECHOVICE 31 0.05 364 SAZAVA ZRUC ns 57 1.76 355 ZELIVKA SOUTICE 21 0.73 364 BLANICE RADONICE 99 0.38 355 SAZAVA NESPEKY 38 4.15 355 MZE STRIBRO 41 1.47 355 UTERSKY P TRPISTY 2 0.01 365 RADBUZA CESKE UDOLI 16 1.20 355 USLAVA KOTEROV 11 0.24 364 KLABAVA NOVA HUT 25 0.34 355 LITAVKA BEROUN 29 0.38 355 ODRAVA JESENICE 37 0.79 355 SVATAVA SVATAVA 21 0.93 355 TEPLA BREZOVA 6 0.38 355 PLOUCNICE BENESOV np 67 1.60 365 LUZ.NISA LIBEREC 25 0.49 355 SMEDA FRYDLANT 16 0.66 355 MORAVA MORAVICANY 83 4.90 355 ROMZE STRAZISKO 2 355 DREVNICE ZLIN 20 0.30 355 MOR.DYJE JANOV 23 0.20 355 JIHLAVA DVORCE 16 0.43 355 JIHLAVA PTACOV 55 1.20 355 OSLAVA OSLAVANY 64 0.62 355 DYJE NOVE MLYNY 249 12.00 355 Lower Elbe water level is bellow the limit for full navigation (275 cm) between Usti nad Labem and Czech-German border since May (fig.4). Recent water levels are between 140 and 145 cm. That means maximal possible ship sink of 80 85 cm not enabling economical operation of navigation.
3 vodní stav v Ústí nad Labem (m) 2.5 2 1.5 1 0.5 0 30.4.2008 0:00 5.5.2008 0:00 10.5.2008 0:00 15.5.2008 0:00 20.5.2008 0:00 25.5.2008 0:00 30.5.2008 0:00 4.6.2008 0:00 9.6.2008 0:00 14.6.2008 0:00 19.6.2008 0:00 24.6.2008 0:00 29.6.2008 0:00 4.7.2008 0:00 9.7.2008 0:00 14.7.2008 0:00 19.7.2008 0:00 24.7.2008 0:00 29.7.2008 0:00 3.8.2008 0:00 8.8.2008 0:00 HLADINA LIMIT PLNOSPLAVNOSTI Fig. 4 - Ústí nad Labem water stage since May 2008, red water stage, blue full navigation limit. Underground water levels and yield decrease since spring months. Most of the observation boreholes and springs are below normal and belong to 37 % (boreholes) resp. 29 % of lowest historical observations. These values are comparable to those measured in 2007 drought (fig.5). 80 70 60 50 % 40 30 20 10 0 2007 2007 2007 2007 2007 2007 2008 2008 2008 2008 2008 2008 2008 7 8 9 10 11 12 1 2 3 4 5 6 7 prameny Fig. 5 Course of underground water levels and yields in the meaning of probability distribution curve rank since July 2007. 50 % means average, lower values indicate drought. There are significant regional and local differences. While boreholes and spring in Silesia and Bohemian-Moravian Highland are close to the normal, central Bohemia and south Moravia show drought (belongs to 15 % of lowest historical observation). vrty
Fig. 6 Springs yield with respect to July long time normal. Red very low, pink low, white normal, pale blue high, blue very high. Fig. 7 Boreholes water level with respect to July long time normal. Red very low, pink low, white normal, pale blue high, blue very high.
Future outlook Long-range meteorological forecast is for normal precipitation and temperature during August. Medium-range meteorological models assume possible more frequent precipitation in the middle of August, however quantitative prediction is not reasonable so far. If the forecast full fill the drought risk and wild fire flood risk will decrease. In the case of torrent precipitation of more than 30 mm some slow increase of water level of small streams could be also expected. Underground waters are expected to be stable or continue in slow decrease.