圖書典藏及影音數位平台

「天花湖水庫工程環境影響評估報告書」經環保署環境影響評估委員會第201次會議決議：「有條件通過環境影響評估審查」，其中訂有生態保措施及環境監測計畫；自民國101年起先行辦理前期的調查與保育評估工作，主要工作包括生態包括生態資源調查分析及資料庫建置、攔河堰周邊環境營造規劃、生態保育規劃等作業。

Ⅰ、Introduction Due to the development needs of Tien Hwa Hu Reservoir, EIA Report was completed and submitted for review. The EIA Committee of EPA has decided on its 201th meeting to “conditionally approve the EIA review”. In 2013, “The Plan of Water Environmental Observation and Investigation in Houlung River (I) - The Investigation and Assessment of Rivulet Ecology Conservation” has suggested to continuously monitor the ecology of Houlung River Basin, and thus 3 sample stations of Houlung River (Dalukeng, Jhuangoushuei, and Jin-gua Bridge) and 3 sample stations of Shahe Creek & Feifong Creek (Shahe Bridge, Nan-Pei Bridge, and Shuang-Fong Bridge) were selected. Ⅱ、Work Scope 1、 Data collection and analysis, including the summary of Houlung River mainstream, Shahe Creek and Feifong Creek; performing flow observation of Feifong Creek and estimating the flow (once per month). 2、 Ecological resources investigation and ecosystem conservation plan, including: (1) Quarter investigation of fishes and crustaceans. The locations cover Dalukeng, Jhuangoushuei, Jin-gua Bridge, Shahe Bridge, Nan-Pei Bridge and Shuang-Fong Bridge. (2) Investigation of algae and aquatic insects each in dry season and wet season. The location is Dalukeng. (3) When finding the protected wild species or migratory species, we should further review whether the reservoir plan will affect the environment or conditions of their habitats, and develop conservation measures. 3、Establishment of ecological resource database Ⅲ、Results of the Investigation 1、Flow observation of Feifong Creek Since February of 2013, on-site flow observation has been performed once per month at Yung-Xing Bridge of Feifong Creek, and flows were estimated as shown in Table 1. We also set up self-recording water level gage at Yung-Xing Bridge to transmit the data since August 22, 2012. 2、Fishes Investigation Totally 26 species of 3,521 fishes from 10 families of 4 orders were recorded in the sample stations. 13 species of them are dominant species, which include Acrossocheilus formosanus, Candidia barbata, Squalidus iijimae, Microphysogobio alticorpus, Formosania lacustre, Opsariichthys pachycephalus, Opsariichthys evolans, Hemimyzon formosanum, Rhinogobius candidianus, Spinibarbus hollandi, Leiocassis taiwanensis, Rhinogobius rubromaculatus and Rhinogobius rubromaculatus. Squalidus iijimae belongs to the endangered species. According to “Taiwan Freshwater Fishes Redbook”, Squalidus iijimae belongs to “Class A Critically Endangered” protected species, Paracheilognathus himantegus, Hemibarbus labeo and Opsariichthys evolans belong to “Class D Nearly Endangered” protected species. In the records, Rhinogobius giurinus, Sicyopterus japonicas, Rhyacichthys aspro and Anguilla marmorata are migratory species; Oreochromis sp., Channa striata, and Spinibarbus hollandi belong to alien species. 3、Crustaceans investigation This year, totally 9 species 1,948 crustaceans from 4 families were recorded. The dominant species are Macrobrachium asperulum, accounting for 82.03% of overall investigation amount. 4 species belong to migratory Decapoda animals, which are Eriocheir hepuensis, Macrobrachium formosense, Macrobrachium nipponense, and Macrobrachium lar. They were found around the reservoir and can be traced back to the sample station of Nan-Pei Bridge and Dalukeng. Neocaridina ketagalanare , Caridina formosae, and Candidiopotamon rathbunae are three dominant species. IⅤ、Ecosystem conservation plan 1、River characteristics and current conditions of indicator species (1) Difference of river characteristics Houlung River and Feifong Creek have different river characteristics, and similarities are largely different for each sample station. The investigation result of 3 sample stations of Houlung River and 3 sample stations of Feifong Creek (Including Shahe Creek) in this year. See Table 2. for details. (2) Current conditions of indicator species According to past investigation and the migration characteristics, Anguilla japonica, Anguilla marmorata, Opsariichthys pachycephalus, Acrossocheilus formosanus, Varicorhinus barbatulus, Squalidus iijimae, Rhinogobius candidianus, Microphysogobio alticorpus, Rhinogobius rubromaculatus, Macrobrachium nipponense, Formosania lacustre, Hemimyzon formosanum, Macrobrachium asperulum, Sicyopterus japonicus, Eriocheir hepuensis are 15 indicator species. A. Shahe Creek & Feifong Creek Varicorhinus barbatulus and Sicyopterus japonicus has not been found at Shahe Creek & Feifong Creek. This year Anguilla japonicas were not found at Shahe Creek & Feifong Creek, and average catch rate for other 12 indicator species keep in good standard. B. Houlung River Eriocheir hepuensis has not been found at upstream of Dalukeng. Anguilla japonica was not found after 2010, and the average catch rate of Formosania lacustre is 9.2 pcs /per time, it’s less than 2010-2011. The average catch rate for other 9 indicator species keep in good standard. 2、Conservation measures of Feifong Creek (1) Current conditions After comparing the difference of flow and species between Feifong Creek (1,394 fishes of 19 species from 7 families, and 1,650 crustaceans of 8 species from 4 families) and Houlung River (2,127 fishes of 18 species from 8 families, and 298 crustaceans of 3 species from 2 families), the results show that Shahe Creek & Feifong Creek are showed highly biodiversity for aquatic animals to habitat. Among the fishes and crustaceans founded in Shahe Creek & Feifong Creek, 5 species recorded are migratory animals. Squalidus iijimae belongs to “endangered species” announced by Agricultural Commission; Opsariichthys evolans and Paracheilognathus himantegus are “nearly endangered fishes” listed in “Taiwan Freshwater Fishes Redbook”. In addition, Lophura swinhoii were also founded during the investigation at Shuang-Fong Bridge; Herpestes urva formosanus were founded in “The Plan of Water Environmental Observation and Investigation in Houlung River (I) - The Investigation and Assessment of Hill Ecology Conservation (1/2)”. These precious animals rely on not only the large amount of crustaceans in the stream as food, but also the sand along the riverbank for breeding. It is necessary to improve the revetment because the concrete has affected the climbing of several animals such as Mauremys mutica and Herpestes urva formosanus; the threats from Alien species should also be improved including Oreochromis sp. and Channa striata. (2) Influence and measures of the reservoir construction A. Changes in the river flow The design of free overflow weir without gate was applied to the dam of Tianhuahu Reservoir. The rainfall of the upstream catchment will be discharged to the downstream of the reservoir, which means the flow of the downstream should be consistent with the current conditions. It is expected that Shahe Creek & Feifong Creek can still maintain the rich ecological water resources. B. Changes in the stream environment After the completion of the reservoir, the channel of 3.5 km in length will be changed into lake, which may cause several animals such as Herpestes urva formosanus to lose half of its foraging sites. The most friendly way is to use the left dam widening zone to reproduce the channel type in the inundated area and maintain a stream of 2~2.5 km in length to connect the original biological pathways of Herpestes urva formosanus. The improvement concepts of 4 riverbank areas have been put forward to help animals such as Herpestes urva formosanus, Mauremys mutica and Ocadia sinensis, to take advantage of the environment of the stream C. Effects on the protected fishes The “endangered” Squalidus iijimae and the “nearly endangered” Opsariichthys evolans have been recorded in Shahe Creek, and no construction of the reservoir was founded near the location. Therefore, there is no significant effect on these two species under the similar conditions and without construction interference. The “nearly endangered” Paracheilognathus himantegus was also founded at Nan-Pei Bridge. This species prefer stable water and can be recovered in the ecological detention pond of the left dam widening zone. Due to the scarce population and narrow distribution of Squalidus iijimae, it is necessary to keep tracking its changes of population. D. Influence and measures of the migratory animals The sample station of Changshou Bridge at the upstream of Shahe Creek was added to the investigation in 2012, and no migratory animals were founded. It shows that the anadromous path of 10 species of migratory animals starts from the outfall of Houlung River passing through the mainstream to Lung-jing Pool and ends in Shahe Creek and Feifong Creek. The 10 species are Rhinogobius giurinus, Anguilla marmorata, Kuhlia marginata, Macrobrachium formosense, Macrobrachium nipponense, Macrobrachium gracilirostre, Macrobrachium jaroense, Macrobrachium lar, Varuna litterata, and Eriocheir hepuensis. Combining the riverbank improvement with the method of reproducing the channel type in the inundated area and maintaining a stream with 2~2.5 km in length, will minimize the effects of reservoir construction on the migratory animals. E. Measures of Alien species Alien species such as Oreochromis sp. and Channa striata, can be gradually cleared by Miaoli River Ecological Conservation Association in the future. 3、Conservation measures of Houlung River Although primary freshwater fishes are dominant in the upstream of Houlung River, but Anguilla marmorata, Sicyopterus japonicas, Kuhlia rupestris, Rhyacichthys aspro, Macrobrachium formosense, Macrobrachium jaroense, Macrobrachium lar, and Varuna litterata were founded as migratory animals at Houlung River. The weir of Dalukeng was originally designed as staged fish way and one natural fish way has been added after the review, which means obstacle to the migratory animals will no longer exist. Other freshwater fishes were also founded to migrate in the river, which are Acrossocheilus formosanus, Candidia barbata, Opsariichthys pachycephalus, Opsariichthys evolans, and Varicorhinus barbatulus. The fish ways mentioned above can ensure these fishes passing through without being blocked. The riprap for the dam of Tian-hua-hu Reservoir was taken from Wen-shuei river. According to the results of 2010~2015, Opsariichthys evolans belong to “nearly endangered” species listed in “Taiwan Freshwater Fishes Redbook”. Therefore, the maintenance of water quality is required in the construction area to avoid discharging high turbidity of muddy water directly into the creek without precipitation. In addition, activities of Lepus sinensis formosus and Sus scrofa taivanus were found near Jin-gua Bridge, so the material areas should be developed by section and by stage. If there is secondary forest zone near the creek, facilties should be installed 1 m away from the zone edge to stop wildlife entering the construction area and getting hurt. 4、Ecological monitoring and supervision feedback “Implementation Framework of Tianhuahu Reservoir Conservation” addressed in 2009, should be established rapidly to arrange the ecological conservation and monitoring. (1) Establish a specific website to publish the monitoring data before construction, during construction and after construction for inquiry. (2) The construction method or facilities of ecological conservation should put interpretive signs at safe locations for the public and visitors. (3) Responsible parties, established according to “Implementation Framework of Tianhuahu Reservoir Conservation”, should contact local government or township office to regularly open “Training courses of ecological conservation” in order to recruit and train the volunteers to take over the operation ( or guiding) of eco-museum and long-term monitoring during the reservoir operation. V、Database Establishment Based on the “format standard of water resources data”, the database of this investigation results was established, including Ecological Investigation Location Map (2C01AA), Location Map of River Water Quality Monitoring Stations (3A01AA), Fishes Investigation Data (2C04AA), Crustaceans Investigation Data (2C04AB).